Error initializer string for array of chars is too long fpermissive

Short answer: Because C and C++ are different languages with different rules.

Long answer: In both cases the reason is that the array is too small for the string literal. The literal consists of the five visible characters, with a zero terminator on the end, so the total size is 6.

In C, you’re allowed to initialise an array with a string that’s too long; extra characters are simply ignored:

C99 6.7.8/14: An array of character type may be initialized by a character string literal, optionally enclosed in braces. Successive characters of the character string literal (including the terminating null character if there is room or if the array is of unknown size) initialize the elements of the array.

The compiler helpfully warns that the string is too large, since it almost certainly indicates an error; but it can’t reject the code unless you tell it to treat warnings as errors.

In C++, the initialiser isn’t allowed to be larger than the array:

C++11 8.5.2/2: There shall not be more initializers than there are array elements.

so, for that language, the compiler should give an error.

In both languages, when you want a character array to be the right size for a string literal initialiser, you can leave the size out and the compiler will do the right thing.

char a[] = "hello";  // size deduced to be 6

Aside from the missing commas in your set of initializers, why not just skip making it a 2-dimensional array of char? You’re only passing the array data to strstr(), and all it wants are null terminated strings. Why not use the more flexible:

char* array[] = { 
    "Becky Warre, 555-1223",
    "Joe Looney, 555-0097",
    "Geri Palmer, 555-8787",
    "Lynn Presnell, 555-1212",
    "Holly Gaddis, 555-8878",
    "Sam Wiggins, 555-0998",
    "Bob Kain, 555-8712",
    "Tim Haynes, 555-7676",
    "Warren Gaddis, 555-9037",
    "Jean James, 555-4939",
    "Ron Palmer, 555-2893",
    NULL
};

Now that the array is just a set of pointers (and it’s terminated with a NULL pointer), the loop can look something like:

char *ptr = NULL;
int i;
for (i = 0; array[i] != NULL; i++)
{
        ptr = strstr(array[i], search);
        if (ptr != NULL)
                cout << array[i];
}

One advantage of this is that you can add new strings to the data without having to update any corresponding ‘size’ numbers. And you’ll never have to worry about the compiler complaining that the array is too small in one dimension or another — it’ll just make the array the size it needs to be.

#include <stdio.h>
int main(void)
{
char a[5]="Hello";
a[0]='y';
puts(a);
for(int i=0;i<5;i++)
printf("%c",a[i]);
return 0;
}

Warning:[Error] initializer-string for array of chars is too long [-fpermissive] enabled by default

[Error] initializer-string for array of chars is too long [-fpermissive]

Решение

char a[] = "hello";  // size deduced to be 6

Другие решения

char a[5]="Hello";

char a[5]="Hello";

Короткий ответ: потому что C и С++ — разные языки с разными правилами.

Длинный ответ: В обоих случаях причина заключается в том, что массив слишком мал для строкового литерала. Литерал состоит из пяти видимых символов с нулевым терминатором на конце, поэтому общий размер равен 6.

В C вы можете инициализировать массив со слишком длинной строкой; дополнительные символы просто игнорируются:

C99 6.7.8/14: массив типа символа может быть инициализирован литералом строковой буквы, необязательно заключенным в фигурные скобки. Последовательные символы символьного строкового литерала (включая завершающий нулевой символ, если есть место или массив неизвестного размера) инициализируют элементы массива.

Компилятор предупреждает, что строка слишком велика, поскольку она почти наверняка указывает на ошибку; но он не может отклонить код, если вы не сообщите ему, чтобы он рассматривал предупреждения как ошибки.

В С++ инициализатор не может быть больше, чем массив:

С++ 11 8.5.2/2: не должно быть больше инициализаторов, чем элементов массива.

поэтому для этого языка компилятор должен сообщить об ошибке.

В обоих языках, когда вы хотите, чтобы массив символов был правильным размером для инициализатора строкового литерала, вы можете оставить размер, и компилятор выполнит правильные действия.

char a[] = "hello";  // size deduced to be 6

Following program compiles fine in C with warnings but fails in compilation in C++. Why? What is the reason?

#include <stdio.h>
int main(void)
{
    char a[5]="Hello";
    a[0]='y';
    puts(a);
    for(int i=0;i<5;i++)
        printf("%c",a[i]);
    return 0;
}

The warning:

Warning:[Error] initializer-string for array of chars is too long [-fpermissive] enabled by default

But if the program is compiled as C++ program then C++ compiler gives following error:

[Error] initializer-string for array of chars is too long [-fpermissive]

I am using GCC 4.8.1 compiler.

Short answer: Because C and C++ are different languages with different rules.

Long answer: In both cases the reason is that the array is too small for the string literal. The literal consists of the five visible characters, with a zero terminator on the end, so the total size is 6.

In C, you’re allowed to initialise an array with a string that’s too long; extra characters are simply ignored:

C99 6.7.8/14: An array of character type may be initialized by a character string literal, optionally enclosed in braces. Successive characters of the character string literal (including the terminating null character if there is room or if the array is of unknown size) initialize the elements of the array.

The compiler helpfully warns that the string is too large, since it almost certainly indicates an error; but it can’t reject the code unless you tell it to treat warnings as errors.

In C++, the initialiser isn’t allowed to be larger than the array:

C++11 8.5.2/2: There shall not be more initializers than there are array elements.

so, for that language, the compiler should give an error.

In both languages, when you want a character array to be the right size for a string literal initialiser, you can leave the size out and the compiler will do the right thing.

char a[] = "hello";  // size deduced to be 6