Parse error before int

Часто встречающиеся ошибки стадии компиляции

Очень часто начинающие программисты впадают в суеверный ужас, когда видят, что компилятор нашел в тексте программы ошибку, но не понимают, в чем она заключается.

А если помножить этот факт на незнание английского языка («чего там ему не нравится. ») и слабое владение синтаксисом C++ («хм, а может, тут нужна точка с запятой…»), то проблема принимает масштаб катастрофы.

Тот факт, что компилятор в силу своих ограниченных возможностей изо всех сил старается объяснить, что конкретно неверно, не спасает ситуацию. Как быть, если гуглить неохота, а спросить не у кого?

В этом посте на правах копипаста с последующим переводом, дополнениями и исправлениями приведу описание наиболее распространенных сообщений об ошибках и предупреждений компилятора. Неприятность кроется в том факте, что разные компиляторы ругаются на одинаковые ошибки по-разному, а некоторые даже не замечают то, что другие принимают за ошибку. Все зависит от совести разработчиков компилятора, даты его выпуска, и др.

В качестве компилятора возьмем g++, который, в частности, может использоваться в среде Code::Blocks. Версия gcc (куда входит g++) для ОС Windows зовется MinGW. По ходу я буду давать аналоги ошибок из лексикона русскоязычной Microsoft Visual C++.

Итак, частые ошибки:

undeclared identifier

doy.cpp: In function ‘int main()’:
doy.cpp:25: ‘DayOfYear’ undeclared (first use this function)
doy.cpp:25: (Each undeclared identifier is reported only once for each function it appears in.)
doy.cpp:25: parse error before ‘;’ token

2) Смысл
Использован идентификатор DayOfYear , но компилятор не нашел его объявления. Он не знает, что такое DayOfYear .

• Вы забыли включить какой-то заголовочный файл ( #include. )
• Вы где-то ошиблись в написании идентификатора (при объявлении или использовании)
• Вы вообще забыли, что эту переменную надо объявить

Попытавшись скомпилировать это в Microsoft Visual C++, вы увидите:

error C2065: DayOfYear: необъявленный идентификатор

cout undeclared

xyz.cpp: In function ‘int main()’:
xyz.cpp:6: ‘cout’ undeclared (first use this function)
xyz.cpp:6: (Each undeclared identifier is reported only once for each function it appears in.)

2) Смысл
Суперклассика. Без комментариев.

• Вы забыли включить
• Вы забыли написать using namespace std;

jump to case label

switch.cpp: In function ‘int main()’:
switch.cpp:14: jump to case label
switch.cpp:11: crosses initialization of ‘int y’

2) Смысл
Смысл туманен

3) Когда бывает
Вы попытались объявить и инициализировать переменную (объект, указатель и т.п.) в метке case оператора выбора switch. Правилами C++ это запрещено.

В Microsoft Visual C++ эта ошибка зовется

error C2360: пропуск инициализации ‘y’ из-за метки ‘case’

Выход: заключите операторы этого case’а в фигурные скобки <>.

multi-line string / unterminated string

using namespace std;

вызовет бурную реакцию компилятора:

string.cpp:7:12: warning: multi-line string literals are deprecated
string.cpp: In function ‘int main()’:
string.cpp:7: ‘so’ undeclared (first use this function)
string.cpp:7: (Each undeclared identifier is reported only once for each function it appears in.)
string.cpp:7: parse error before ‘Mary’
string.cpp:8:28: warning: multi-line string literals are deprecated
string.cpp:8:28: missing terminating » character
string.cpp:7:12: possible start of unterminated string literal

2) Смысл
Компилятор думает, что мы хотим создать строковую константу с содержащимся в ней переносом строки, что-то типа

что не поддерживается языком. Также делается предположение о том, что мы, возможно, забыли поставить кавычки в конце первой строки. Собственно, так оно и есть.

3) Когда бывает
Когда не соблюдается правильное количество и положение кавычек в строковых литералах. Надо быть внимательнее.

Microsoft Visual C++ со свойственной ему детской непосредственностью, отметит, что нельзя делать переносы в строках и возмутится, где точка с запятой:

error C2001: newline в константе
error C2146: синтаксическая ошибка: отсутствие «;» перед идентификатором «cout»

comparison between signed and unsigned integer expressions

xyz.cpp: In function ‘int main()’:
xyz.cpp:54: warning: comparison between signed and unsigned integer expressions

2) Смысл
Это — предупреждение компилятора, которое говорит о том, что мы пытаемся сравнить (==, и т.д.) целочисленное выражение (может принимать положительные, отрицательные значения и 0) и беззнаковое целочисленное выражение (может быть только положительным, либо 0).

3) Когда бывает
Собственно, тогда и бывает. Напомню, что тип int по умолчанию знаковый, а некоторые функции (например, vector::size() ) возвращают unsigned int .
К примеру, следующий на первый взгляд безобидный код вызовет описываемое предупреждение:

Следует помнить, что в памяти знаковые и беззнаковые типы имеют разные внутренние представления, поэтому надо быть чертовски осторожными с указателями.

В Microsoft Visual C++ предупреждение выглядит так:

suggest parentheses around assignment used as truth value

xyz.cpp: In function `int main()’:
xyz.cpp:54: warning: suggest parentheses around assignment used as truth value

2) Смысл
Тоже классика. Компилятор предполагает (и в 99% случаев прав), что вы по ошибке включили в скобки в качестве условия для if/while/for вместо условного выражения выражение присваивания.

3) Когда бывает
Чаще всего — в if ‘ах, когда вместо «==» используется «=»

if (length = maxLength)

if (length == maxLength)

Заминка в том, что это не ошибка, т.к. в скомпилированной программе (если мы проигнорируем предупреждение) выражение присваивания (которое возвращает значение правого аргумента) во всех случаях, кроме тех, когда оно вернет 0 , будет преобразовано к true .

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Parse error before

Hi, I am migrating the C (messy)programs from HP-UX(cc compiler) to AIX(gcc 3.3.2)

Please help me to resolve this.
Note: Since this is my first post on a forum, so please apologize, if the inputs provided are in not in a good format.The line numbers are mentioned in the sour

You need to take the phrase «parse error before» literally. That implies a C syntax error on your part.

for example, the first refers to this:

Start at the top of the digest and work your way through each error. Sometimes if you click the error in a IDE, the line will be highlighted for you.

Have you actually bothered to look at the code corresponding to the error messages?

For example, line 635 (which triggers the first error) is

That sort of placement of digits, followed the the semi-colon, then a valid token is invalid. Hence the compiler complaining about «parse error before . «.

I haven’t looked further than that, but given that the cause of the first two errors is blindingly obvious, I suggest you apply effort yourself to find the other errors.

Right 98% of the time, and don’t care about the other 3%.

If I seem grumpy or unhelpful in reply to you, or tell you you need to demonstrate more effort before you can expect help, it is likely you deserve it. Suck it up, Buttercup, and read this, this, and this before posting again.

@grumpy I think those digits followed by the semi-colon are for us to find the lines aren’t they?
Anyway he is missing some brackets after the if statement it should be :

I’m on a hurry so couldn’t take the time to look at the full code but maybe the errors are propagating from those missing brackets try to correct and compile again. Hope it helps

P.S: sorry I think whiteflags was faster and better explaining what you should do so follow his tips.

Last edited by beta3designs; 08-19-2011 at 05:30 AM .

Thanks for your precious time to look into this 🙂

And, yes as you mentioned the line numbers like «635:», is just to show you the line numbers.

However, I’ll try to figure it out in the meantime. What I dont understand is, the same code works on HP UX(cc) but not on AIX.

Not to worry. *everything* HP is weird.

If you can, check your HPUX sources; if cc accepts

without parentheses, then you probably let HP know about it.

Most compilers support «extensions», and this is presumably one of them. That generally means some feature that the vendor, or its development team, think is a good thing.

In this case, someone on the HP UX(cc) development team probably had a background in Pascal, or some language derived from Pascal, like Ada.

It is the sort of thing that would be introduced by a programming language zealot/bigot, not through a management decision. A lot of people with a Pascal background think C needs to be improved so it becomes more like Pascal.

Right 98% of the time, and don’t care about the other 3%.

If I seem grumpy or unhelpful in reply to you, or tell you you need to demonstrate more effort before you can expect help, it is likely you deserve it. Suck it up, Buttercup, and read this, this, and this before posting again.

Haha. I think either you or they have drastically misunderstood the meaning of the word «improve».

In my opinion, Pascal is a hideously repulsive language whose sole redeeming feature is that it’s not Haskell.

Haha. I think either you or they have drastically misunderstood the meaning of the word «improve».

In my opinion, Pascal is a hideously repulsive language whose sole redeeming feature is that it’s not Haskell.

I didn’t suggest that making C look like Pascal represents an improvement. Some people would though.

Programming language bigotry does not only appear as advocacy of a particular language though, as you have demonstrated.

Right 98% of the time, and don’t care about the other 3%.

If I seem grumpy or unhelpful in reply to you, or tell you you need to demonstrate more effort before you can expect help, it is likely you deserve it. Suck it up, Buttercup, and read this, this, and this before posting again.

Bigotry arises from prejudice- i.e. judging things before you really know anything about them. If I started ranting about ALGOL or COBOL, which I’ve never used, because I’d heard other people say they’re useless and outdated you might have a point. My dislike of the two languages I mentioned come from having used them, and I certainly don’t badmouth other languages just because they’re not my first choice. Still have a soft spot for BASIC since that was the language I learnt as a kid (self taught- result was goto-riddled spaghetti code hell until I learned better), and I don’t mind Fortran at all.

I studied Haskell for a semester at university and I didn’t like it because it was slow and full of confusing circumlocutions; although looking back I can see it improved my understanding of C functions, particularly recursion, and also helped me do more with shell scripts.

Pascal annoyed me, firstly because its weird structure isn’t to my taste at all, and secondly because it has this vibe that it’s enforcing someone else’s programming philosophy on me rather than allowing me the freedom to code in my own style. This tends to make me defensive when I hear of Pascal trying to encroach on C’s turf. Another reason I believe C is superior is that C code translated into Pascal tends to still be somewhat elegant, while Pascal translated to C usually isn’t. C has a kind of common sense simplicity and flexibility that other languages don’t, and that’s why I like it.

I don’t think making a judgment on a programming language based on my experiences and impressions of it make me a bigot.

Bigot (n): someone who is intolerant of any differing creed, belief, opinion, or preference.

TheBigH, it is fine, as you have done in your last post, to give a basis for your comments. That way people can decide, for themselves, if your views are relevant to them and their circumstances. Your previous post made blanket statements in an absolute manner, so I interpreted that as bigotry. If you don’t like being described as a bigot, try to remember to provide context when you express judgements.

What annoys you about Pascal is that it is doing exactly what it was designed to do: encouraging specific practices that, when Pascal was designed, were considered best practices for structured programming and data structures. Just because a language isn’t to your taste, doesn’t mean it is horrid for everyone.

Haskell is a functional programming language. Functional programming tends to annoy people who are not used to that paradigm.

There are anti-C bigots who hate exactly the features you love about C: the flexibility that makes it easier to get in trouble, things like pointers that really can really be used to screw things up.

Right 98% of the time, and don’t care about the other 3%.

If I seem grumpy or unhelpful in reply to you, or tell you you need to demonstrate more effort before you can expect help, it is likely you deserve it. Suck it up, Buttercup, and read this, this, and this before posting again.

Источник

GCC Debugging/g++/Errors

Contents

abstract declarator ‘TYPE’ used as declaration [ edit | edit source ]

• Message found in GCC version 4.5.1
  • often grouped together with:
    • member ‘DATA_MEMBER’ with constructor not allowed in anonymous aggregate
    • member ‘DATA_MEMBER’ with destructor not allowed in anonymous aggregate
    • member ‘DATA_MEMBER’ with copy assignment operator not allowed in anonymous aggregate
• a class or struct is missing a name:

• a header file has a class or struct with a name already used inside ifndef, define statements

call of overloaded ‘FUNCTION’ is ambiguous [ edit | edit source ]

‘VARIABLE’ cannot appear in a constant-expression [ edit | edit source ]

‘VARIABLE’ cannot be used as a function [ edit | edit source ]

• Message found in GCC version 4.5.1
• make sure the variable name does not have an underscore in it (compiler weirdness)
• you’re using the same name for a variable name and a function inside a function definition

conversion from ‘TYPE’ to non-scalar type ‘TYPE’ requested [ edit | edit source ]

• Message found in GCC version 4.5.1
• type conversion error, look for missing «::» syntax or missing parenthesis
• possibly a casting error
• a class member function returns a value that does not match the function’s declared return type

could not convert ‘STATEMENT’ to ‘bool’ [ edit | edit source ]

• Message found in GCC versions 3.2.3, 4.5.1
• you a mistyped comparison operator (e.g., using: «=» instead of «==»)
• you used an incorrect return type for the called function’s definition

• you’re using an invalid argument for a conditional statement

declaration of ‘FUNCTION’ outside of class is not definition [ edit | edit source ]

• Message found in GCC versions 3.2.3, 4.5.1
• try using ‘=’ to initialize a value instead of parenthesis
• you used a semicolon or comma between a constructor and an initializer list instead of a colon
• you left a semicolon before the body of a function definition

declaration of ‘VARIABLE’ shadows a parameter [ edit | edit source ]

• Message found in GCC versions 3.2.3, 4.5.1
• you’re redefining a variable name that’s already in use, possibly declared in the function’s parameter list

‘TYPE’ does not name a type [ edit | edit source ]

• Message found in GCC version 4.5.1
  • in GCC version 3.2.3 sometimes reported as: syntax error before ‘CHARACTER’ token
  • in GCC version 4.0.1, sometimes reported as: ISO C++ forbids declaration
    • e.g.: ISO C++ forbids declaration of ‘vector’ with no type
• you left out an object’s name qualifier or using directive

• make sure you didn’t mistype the scope operator «::», e.g.: «name:name» instead of «name::name»
• make sure you included the required libraries

• a header file is listed after a file that makes use of it in the include directives

expected ‘TOKEN’ before ‘TOKEN’ token [ edit | edit source ]

• Message found in GCC versions 3.2.3, 4.5.1
  • in GCC version 3.2.3 sometimes reported as: syntax error before ‘CHARACTER’ token
• check for a missing comma or parenthesis in a function’s parameters
• check for a missing semicolon
  • e.g.: expected ‘,’ or ‘;’ before ‘TOKEN’

• possibly from a double namespace definition, or a fully-qualified (e.g., std::cout) name already under a ‘using’ directive
• possible missing ‘ >’ operator in a cin/cout statement

expected primary-expression before ‘TOKEN’ [ edit | edit source ]

expected unqualified-id before [ edit | edit source ]

• Message found in GCC version 4.5.1
• check your syntax for missing, misplaced, or erroneous characters
• expected unqualified-id before ‘(‘ token
  • e.g.: parentheses in a class name

• expected unqualified-id before ‘return’
  • e.g.: missing opening brace in a conditional statement

incompatible types in assignment of ‘TYPE’ to ‘TYPE’ [ edit | edit source ]

• Message found in GCC versions 4.5.1
• you’re trying to assign to or initialize a character array using a character pointer
  • e.g.: incompatible types in assignment of ‘const char*’ to ‘char [10]’

• improperly accessing elements of a 2D array

invalid conversion from ‘TYPE’ to ‘TYPE’ [ edit | edit source ]

• Message found in GCC versions 3.2.3, 4.5.1
• make sure parentheses were not left out of a function name
• make sure you are passing a function the correct arguments

invalid operands of types ‘TYPE’ and ‘TYPE’ to binary ‘FUNCTION’ [ edit | edit source ]

• Message found in GCC version 4.5.1
• You’re trying to concatenate to C string arguments with the addition operator

invalid use of template-name [ edit | edit source ]

is not a member of [ edit | edit source ]

• Message found in GCC versions 4.5.1
• check for a missing header include

example: ‘cout’ is not a member of ‘std’

‘TYPE’ is not a type [ edit | edit source ]

• Message found in GCC version 4.5.1
  • in GCC version 3.2.3 reported as: type specifier omitted for parameter ‘PARAMETER’
• you mistyped a template parameter in a function declaration

• an included header file does not have the correct libraries included in the source file to implement it:
  • e.g.: you’re using #include «bar.h» without including the «foo.h» that «bar.h» needs to work
• Check that there are no methods with the same name as ‘TYPE’.

‘CLASS_MEMBER’ is private within this context [ edit | edit source ]

• Message found in GCC versions 3.2.3, 4.5.1
• usually reported in the format:
  • (LOCATION_OF_PRIVATE_DATA_MEMBER) error: ‘DATA_MEMBER’ is private
  • (LOCATION_OF_CODE_ACCESSING_PRIVATE_DATA) error: within this context
• Message usually results from trying to access a private data member of a class or struct outside that class’s or struct’s definition
• Make sure a friend member function name is not misspelled

• make sure a read only function is using a ‘const’ argument type for the class
• make sure functions that alter data members are not const
• check for derived class constructors implicitly accessing private members of base classes

possible fix, assign the whole object rather than part of it:

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Parse error before

Hi, I am migrating the C (messy)programs from HP-UX(cc compiler) to AIX(gcc 3.3.2)

Please help me to resolve this.
Note: Since this is my first post on a forum, so please apologize, if the inputs provided are in not in a good format.The line numbers are mentioned in the sour

You need to take the phrase «parse error before» literally. That implies a C syntax error on your part.

for example, the first refers to this:

Start at the top of the digest and work your way through each error. Sometimes if you click the error in a IDE, the line will be highlighted for you.

Have you actually bothered to look at the code corresponding to the error messages?

For example, line 635 (which triggers the first error) is

That sort of placement of digits, followed the the semi-colon, then a valid token is invalid. Hence the compiler complaining about «parse error before . «.

I haven’t looked further than that, but given that the cause of the first two errors is blindingly obvious, I suggest you apply effort yourself to find the other errors.

Right 98% of the time, and don’t care about the other 3%.

If I seem grumpy or unhelpful in reply to you, or tell you you need to demonstrate more effort before you can expect help, it is likely you deserve it. Suck it up, Buttercup, and read this, this, and this before posting again.

@grumpy I think those digits followed by the semi-colon are for us to find the lines aren’t they?
Anyway he is missing some brackets after the if statement it should be :

I’m on a hurry so couldn’t take the time to look at the full code but maybe the errors are propagating from those missing brackets try to correct and compile again. Hope it helps

P.S: sorry I think whiteflags was faster and better explaining what you should do so follow his tips.

Last edited by beta3designs; 08-19-2011 at 05:30 AM .

Thanks for your precious time to look into this 🙂

And, yes as you mentioned the line numbers like «635:», is just to show you the line numbers.

However, I’ll try to figure it out in the meantime. What I dont understand is, the same code works on HP UX(cc) but not on AIX.

Not to worry. *everything* HP is weird.

If you can, check your HPUX sources; if cc accepts

without parentheses, then you probably let HP know about it.

Most compilers support «extensions», and this is presumably one of them. That generally means some feature that the vendor, or its development team, think is a good thing.

In this case, someone on the HP UX(cc) development team probably had a background in Pascal, or some language derived from Pascal, like Ada.

It is the sort of thing that would be introduced by a programming language zealot/bigot, not through a management decision. A lot of people with a Pascal background think C needs to be improved so it becomes more like Pascal.

Right 98% of the time, and don’t care about the other 3%.

If I seem grumpy or unhelpful in reply to you, or tell you you need to demonstrate more effort before you can expect help, it is likely you deserve it. Suck it up, Buttercup, and read this, this, and this before posting again.

Haha. I think either you or they have drastically misunderstood the meaning of the word «improve».

In my opinion, Pascal is a hideously repulsive language whose sole redeeming feature is that it’s not Haskell.

Haha. I think either you or they have drastically misunderstood the meaning of the word «improve».

In my opinion, Pascal is a hideously repulsive language whose sole redeeming feature is that it’s not Haskell.

I didn’t suggest that making C look like Pascal represents an improvement. Some people would though.

Programming language bigotry does not only appear as advocacy of a particular language though, as you have demonstrated.

Right 98% of the time, and don’t care about the other 3%.

If I seem grumpy or unhelpful in reply to you, or tell you you need to demonstrate more effort before you can expect help, it is likely you deserve it. Suck it up, Buttercup, and read this, this, and this before posting again.

Bigotry arises from prejudice- i.e. judging things before you really know anything about them. If I started ranting about ALGOL or COBOL, which I’ve never used, because I’d heard other people say they’re useless and outdated you might have a point. My dislike of the two languages I mentioned come from having used them, and I certainly don’t badmouth other languages just because they’re not my first choice. Still have a soft spot for BASIC since that was the language I learnt as a kid (self taught- result was goto-riddled spaghetti code hell until I learned better), and I don’t mind Fortran at all.

I studied Haskell for a semester at university and I didn’t like it because it was slow and full of confusing circumlocutions; although looking back I can see it improved my understanding of C functions, particularly recursion, and also helped me do more with shell scripts.

Pascal annoyed me, firstly because its weird structure isn’t to my taste at all, and secondly because it has this vibe that it’s enforcing someone else’s programming philosophy on me rather than allowing me the freedom to code in my own style. This tends to make me defensive when I hear of Pascal trying to encroach on C’s turf. Another reason I believe C is superior is that C code translated into Pascal tends to still be somewhat elegant, while Pascal translated to C usually isn’t. C has a kind of common sense simplicity and flexibility that other languages don’t, and that’s why I like it.

I don’t think making a judgment on a programming language based on my experiences and impressions of it make me a bigot.

Bigot (n): someone who is intolerant of any differing creed, belief, opinion, or preference.

TheBigH, it is fine, as you have done in your last post, to give a basis for your comments. That way people can decide, for themselves, if your views are relevant to them and their circumstances. Your previous post made blanket statements in an absolute manner, so I interpreted that as bigotry. If you don’t like being described as a bigot, try to remember to provide context when you express judgements.

What annoys you about Pascal is that it is doing exactly what it was designed to do: encouraging specific practices that, when Pascal was designed, were considered best practices for structured programming and data structures. Just because a language isn’t to your taste, doesn’t mean it is horrid for everyone.

Haskell is a functional programming language. Functional programming tends to annoy people who are not used to that paradigm.

There are anti-C bigots who hate exactly the features you love about C: the flexibility that makes it easier to get in trouble, things like pointers that really can really be used to screw things up.

Right 98% of the time, and don’t care about the other 3%.

If I seem grumpy or unhelpful in reply to you, or tell you you need to demonstrate more effort before you can expect help, it is likely you deserve it. Suck it up, Buttercup, and read this, this, and this before posting again.

Источник

#include <stdio.h>
#include <string.h>
 
int checkVar (char s[3])
{
    if ((((s[0] <= 90) && (s[0] >= 65)) || ((s[0] >= 97) && ( s[0] <= 122))) && (s[1] == 32))
    return 1;
    printf ("Perem napis ne prav");
    return 0;
}
 int chekLeft(char s[3])
 {
    return checkVar(s);
 }
  int checkRight ( char s[255])
  {
    int i, j; char s1[3], s2[3], s3[3];
    if ((strlen(s) == 9) && (s[2] ==':') && (s[3] == '=') && ((s[6] == '+') || (s[6] == '-') || (s[6] == '*')))
    { 
      for (i = 0; i < 2; i++) 
        {
            s1[i] = s[i]; s2[i] = s[i + 4]; s3[i] = s[i + 7]; 
            s1[3] = ''; s2[3] = ''; s3[3] = '';
        }
      return checkVar(s1)*checkVar(s2)*checkVar(s3); 
    }
    if ((strlen(s) == 6) && (s[2] ==':') && (s[3] == '=')) 
     { 
       for (i = 0; i < 2; i++) 
       {
            s1[i] = s[i]; s2[i] = s[i + 4];
            s1[3] = ''; s2[3] = '';
       }
       return checkVar(s1)*checkVar(s2);
     }
  printf ("oshibka zapisi");
  return 0;
  }
    int checkAssign (char s[255])
    {
        int i, j; char s1[3]; char s2[255];
        for (i = 0; i < strlen(s); i++)
        {
            if ((s[i] ==':') && (s[i + 1] == '=')) 
            {
                strncpy(s1, s, 2); s1[3] = '';
                for (j = i + 2; j < strlen(s); j++)
                s2[j -i - 2] = s[j]; s2[j+1] = '';
            return checkLeft(s1)* checkRight(s2);
            }
            printf ("Nekorrektna zapis");
            return 0;
        }
    int checkLinear(char s[255])
    {
      int i, j; 
      for (i = 0; i < strlen(s); i++)
      if (s[i] == ';')
      {
        for (j = 0; j < i; j++) 
        s1[j] = s[j]; s1[j+1] = '';
        for (j = i + 2; j < strlen(s); j++) 
        s2[j-i-2] = s[j]; s1[j+1] = '';
        return checkAssign(s1)*checkAssign(s2);
      }
      return checkAssign(s);
    }
    int main ()
    {
        char s[255];
        s[35] = "X :=A ;Y :=X +A ;I :=X -X ;Z :=Z *G ";
        
        checkLinear(s);
        return 0;
    }

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while (location != NULL){ 
  if (item == listPtr->item ){ 
    return true; 
  } 
} // while ends 
// now we have an else without an if 
// statement 
else{ 
  return false; 
}

// This is the implementation file for class List

#include <iostream>
#include <fstream>
#include <stddef.h>		// to access NULL
#include "List.h"
using namespace std;

typedef NodeType* NodePtr;

struct NodeType
{
    ItemType item;
    NodePtr  next;
};

List::List()
// Post:  listPtr is set to NULL.
{
    listPtr = NULL;
}

//***********************************************************
List::List(const List&  otherList)
// Copy-constructor for List.
{
    NodeType* ptr1;
	NodeType* ptr2;

	if (otherList.listPtr == NULL)
		{ listPtr = NULL; }
	else
	{
		listPtr = new NodeType;
		listPtr->item = otherList.listPtr->item;
		ptr1 = otherList.listPtr->next;
		ptr2 = listPtr;
		while (ptr1 != NULL)
		{ ptr2->next = new NodeType;
		  ptr2 = ptr2->next;
		  ptr2->item = ptr1->item;
		  ptr1 = ptr1->next;
		}
	ptr2->next = NULL;
	}
}

//***********************************************************
bool  List::IsThere(ItemType  item) const
// Post: If item is in the list IsThere is
//       True; False, otherwise.
{
	NodeType* location = listPtr;

    while (location != NULL)
          { if (item == listPtr->item )
               { return true; } }
	return false;
}

//***********************************************************
void  List::Insert(ItemType  item)
// Pre:  item is not already in the list.
// Post: item is the first item in the list.
{
	NodeType* location;

	if (IsThere(item) == false)
	{ location = new NodeType;
	  location->item = item;
	  location->next = listPtr;
	  listPtr = location;
	}
}

//***********************************************************
void  List::Delete(ItemType  item)
// Pre:  item is in the list.
// Post: item is no longer in the list.
{
	NodeType* location = listPtr;
	NodeType* tempLocation;

	if (IsThere(item) == true)
		{ tempLocation = location->next;
		  listPtr = listPtr->next;
		}
	else
	    {
		  while (IsThere(item) == true)
			     { location = location->next; }

		  tempLocation = location->next;
		  location->next = (location->next)->next;
	    }
	delete tempLocation;
}

//***********************************************************
void  List::Print() const
// Post: Items on the list are printed on the screen.
{
	NodeType* location = listPtr;

	while (location != NULL)
		  { cout << location->item << endl;
	        location = location->next; }
}

//***********************************************************
int  List::Length() const
// Post: Number of items have been counted; result returned.
{
    NodeType* location = listPtr;
	int length = 0;

	while (location != NULL)
		  { location = location->next;
			length++; }
	return length;
}

//***********************************************************
List::~List()
// Post: All the components are deleted.
{
    NodeType* tempPtr;

	while (listPtr != NULL)
	{
		tempPtr = listPtr;
		listPtr = listPtr->next;
		delete tempPtr;
	}
}


int main ()
{
	ifstream InData;
	InData.open ("int.dat");
	while (InData)
	{ List.Insert(InData); }
    int length = List.Length();
	cout << "There are " << length << " many items in this list." << endl;
	List.Print();

	system ("pause");
	return 0;
}

itemType element; 
  
  ifstream InData;
  InData.open ("int.dat");
  if (inData.isopen()){
    while (InData >> element){    
      List.Insert(element); 
    }
  }

Reply to this topic

Очень часто начинающие программисты впадают в суеверный ужас, когда видят, что компилятор нашел в тексте программы ошибку, но не понимают, в чем она заключается.

А если помножить этот факт на незнание английского языка («чего там ему не нравится?..») и слабое владение синтаксисом C++ («хм, а может, тут нужна точка с запятой…»), то проблема принимает масштаб катастрофы.

Тот факт, что компилятор в силу своих ограниченных возможностей изо всех сил старается объяснить, что конкретно неверно, не спасает ситуацию. Как быть, если гуглить неохота, а спросить не у кого?

В этом посте на правах копипаста с последующим переводом, дополнениями и исправлениями приведу описание наиболее распространенных сообщений об ошибках и предупреждений компилятора. Неприятность кроется в том факте, что разные компиляторы ругаются на одинаковые ошибки по-разному, а некоторые даже не замечают то, что другие принимают за ошибку. Все зависит от совести разработчиков компилятора, даты его выпуска, и др.

В качестве компилятора возьмем g++, который, в частности, может использоваться в среде Code::Blocks. Версия gcc (куда входит g++) для ОС Windows зовется MinGW. По ходу я буду давать аналоги ошибок из лексикона русскоязычной Microsoft Visual C++.

Итак, частые ошибки:

undeclared identifier

1) Пример

doy.cpp: In function 'int main()':
doy.cpp:25: 'DayOfYear' undeclared (first use this function)
doy.cpp:25: (Each undeclared identifier is reported only once for each function it appears in.)
doy.cpp:25: parse error before ';' token

2) Смысл
Использован идентификатор DayOfYear, но компилятор не нашел его объявления. Он не знает, что такое DayOfYear.

3) Когда бывает

• Вы забыли включить какой-то заголовочный файл (#include...)
• Вы где-то ошиблись в написании идентификатора (при объявлении или использовании)
• Вы вообще забыли, что эту переменную надо объявить

Попытавшись скомпилировать это в Microsoft Visual C++, вы увидите:

error C2065: DayOfYear: необъявленный идентификатор

cout undeclared

1) Пример

xyz.cpp: In function 'int main()':
xyz.cpp:6: 'cout' undeclared (first use this function)
xyz.cpp:6: (Each undeclared identifier is reported only once for each function it appears in.)

2) Смысл
Суперклассика. Без комментариев.

3) Когда бывает

• Вы забыли включить <iostream>
• Вы забыли написать using namespace std;

jump to case label

1) Пример

switch.cpp: In function 'int main()':
switch.cpp:14: jump to case label
switch.cpp:11: crosses initialization of 'int y'

2) Смысл
Смысл туманен

3) Когда бывает
Вы попытались объявить и инициализировать переменную (объект, указатель и т.п.) в метке case оператора выбора switch. Правилами C++ это запрещено.

В Microsoft Visual C++ эта ошибка зовется

error C2360: пропуск инициализации 'y' из-за метки 'case'

Выход: заключите операторы этого case’а в фигурные скобки {}.

multi-line string / unterminated string

1) Пример
Программка

#include <iostream>

using namespace std;

int main()
{
cout << "Bob is my buddy;
cout << "and so is Mary" << endl;
}

вызовет бурную реакцию компилятора:

string.cpp:7:12: warning: multi-line string literals are deprecated
string.cpp: In function 'int main()':
string.cpp:7: 'so' undeclared (first use this function)
string.cpp:7: (Each undeclared identifier is reported only once for each function it appears in.)
string.cpp:7: parse error before 'Mary'
string.cpp:8:28: warning: multi-line string literals are deprecated
string.cpp:8:28: missing terminating " character
string.cpp:7:12: possible start of unterminated string literal

2) Смысл
Компилятор думает, что мы хотим создать строковую константу с содержащимся в ней переносом строки, что-то типа

"Hello
world!"

что не поддерживается языком. Также делается предположение о том, что мы, возможно, забыли поставить кавычки в конце первой строки. Собственно, так оно и есть.

3) Когда бывает
Когда не соблюдается правильное количество и положение кавычек в строковых литералах. Надо быть внимательнее.

Microsoft Visual C++ со свойственной ему детской непосредственностью, отметит, что нельзя делать переносы в строках и возмутится, где точка с запятой:

error C2001: newline в константе
error C2146: синтаксическая ошибка: отсутствие ";" перед идентификатором "cout"

comparison between signed and unsigned integer expressions

1) Пример

xyz.cpp: In function 'int main()':
xyz.cpp:54: warning: comparison between signed and unsigned integer expressions

2) Смысл
Это — предупреждение компилятора, которое говорит о том, что мы пытаемся сравнить (==, и т.д.) целочисленное выражение (может принимать положительные, отрицательные значения и 0) и беззнаковое целочисленное выражение (может быть только положительным, либо 0).

3) Когда бывает
Собственно, тогда и бывает. Напомню, что тип int по умолчанию знаковый, а некоторые функции (например, vector::size()) возвращают unsigned int.
К примеру, следующий на первый взгляд безобидный код вызовет описываемое предупреждение:

for (int i = 0; i < grades.size(); i++)
{
// ...
}

Следует помнить, что в памяти знаковые и беззнаковые типы имеют разные внутренние представления, поэтому надо быть чертовски осторожными с указателями.

В Microsoft Visual C++ предупреждение выглядит так:

warning C4018: <: несоответствие типов со знаком и без знака

suggest parentheses around assignment used as truth value

1) Пример

xyz.cpp: In function `int main()':
xyz.cpp:54: warning: suggest parentheses around assignment used as truth value

2) Смысл
Тоже классика. Компилятор предполагает (и в 99% случаев прав), что вы по ошибке включили в скобки в качестве условия для if/while/for вместо условного выражения выражение присваивания.

3) Когда бывает
Чаще всего — в if‘ах, когда вместо "==" используется "="

if (length = maxLength)

вместо

if (length == maxLength)

Заминка в том, что это не ошибка, т.к. в скомпилированной программе (если мы проигнорируем предупреждение) выражение присваивания (которое возвращает значение правого аргумента) во всех случаях, кроме тех, когда оно вернет 0, будет преобразовано к true.

Ссылки для дальнейшего изучения
Ошибки построения Microsoft Visual C++
GCC Compiler error messages
GCC Warnings

P.S. Следует отметить, что кроме ошибок стадии компиляции встречаются (гораздо реже) ошибки препроцессора (например, если не найден заголовочный файл <iostram>), ошибки стадии компоновки (можно избежать, если научиться пользоваться средой программирования) и — самый гнусный тип ошибок! — ошибки стадии выполнения. Т.н. runtime error. С ними может справиться только голова программиста, вооруженная отладчиком.