Cout was not declared in this scope как исправить

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What’s wrong with the following code? (Hint: there are two errors)

#include<iostream>
using namespace std;
 
int main(){
 
  int foo;
 
  for(int i = 0, i<100, i++) {
    foo++;
    cout << foo << endl;
  }
  return 0;
}

When compiled this yields:

junk.cpp:9: error: expected initializer before '<' token

junk.cpp:13: error: expected primary-expression before 'return‘

junk.cpp:13: error: expected `;' before 'return‘

junk.cpp:13: error: expected primary-expression before 'return‘

junk.cpp:13: error: expected `)' before 'return‘

First, the parameters of the for loop need to be separated by semicolons, not commas.

for(int i = 0; i<100; i++) {
    foo++;
    cout << foo << endl;
  }

Now look at this sample output of the corrected code:

-1208637327

-1208637326

-1208637325

-1208637324

-1208637323

-1208637322

Why the weird values? Because we never initialized foo before incrementing it.

 int foo = 0;

Two things to check here:

(1) Did you add

 #include<iostream> 

to your list of headers?
(2) Did you add

 using namespace std; 

after your #includes?

Add

 #include<cstdio> 

to your list of headers. Note if you are coming from C programming, adding
#include<cstdio> is preferred in C++ over #include <stdio.h>.

junk.cpp:8: warning: cannot pass objects of non-POD type 'struct std::string' through '…'; call will abort at runtime

junk.cpp:8: warning: format '%s' expects type 'char*', but argument 2 has type 'int‘

What this usually means is that you forgot to append .c_str() to the name of your string variable when using printf.

This error occurred when trying to compile the following code:

int main(){
 
  string foo = "dog";
  printf("This animal is a %s.n",foo);
  return 0;
}

Simply appending to .c_str() to “foo” will fix this:

printf("This animal is a %s.n",foo.c_str());

The reason you got this error is because printf is a C function and C handles strings differently than C++

junk.cpp:8: error: invalid use of member (did you forget the '&' ?)

What this usually means is that you forget to add () to the end of a function call.

Ironically, every time I see this it is never because I forgot the ‘&’.
This error occurred when trying to compile the following code:

int main(){
 
  string foo = "dog";
  printf("This animal is a %s.n",foo.c_str);
 
  return 0;
}

Simply adding the open and close parentheses () will take care of this for you:

printf("This animal is a %s.n",foo.c_str());

trycredit.cpp:86: error: request for member 'print' in 'card', which is of non-class type 'CreditCard*‘

What this usually means is that you are using a ‘.’ between the class pointer and the function you are trying to call.
Here is an example from the CreditCard lab:

void useCard(CreditCard *card, int method) {
  //Used to access the methods of the class
 
  if (method==1) {
    card.print();
  }

Since card is a CreditCard* we need → rather than . Fixed:

  if (method==1) {
    card->print();
  }

This error usually means you need to add a destructor to your myClass.cpp/myClass.inl code.
If you don’t want to implement a real destructor at this point, you can write something like this:

myClass::~myClass(){}

So long as the destructor exists, you should now be able to compile fine. Of course,
implement a real destructor at a later point.

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error: ‘cout’ was not declared in this scope

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#include <iostream>

using namespace std;

double height, weight;
double bmiCal (double height, double weight);

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using std::cout;
using std::cin;
using std::endl;

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