'cout' was not declared in this scope

Question

I have a C++ program:

test.cpp

#include<iostream>

int main()
{
    char t = 'f';
    char *t1;
    char **t2;
    cout<<t;    //this causes an error, cout was not declared in this scope
    return 0;
}

I get the error:

'cout' was not declared in this scope

Why?

I'm wondering how many times this got asked here. – Mar 03 '13 at 12:49 — , Mar 03 '13 at 12:49
I don't understand why this is closed as "too localized"? – Chris_Rands Jun 15 '18 at 08:13 — Chris_Rands, Jun 15 '18 at 08:13

score 138 · Accepted Answer · edited Aug 19 '19 at 18:09

138

Put the following code before int main():

using namespace std;

And you will be able to use cout.

For example:

#include<iostream>
using namespace std;
int main(){
    char t = 'f';
    char *t1;
    char **t2;
    cout<<t;        
    return 0;
}

Now take a moment and read up on what cout is and what is going on here: http://www.cplusplus.com/reference/iostream/cout/

Further, while its quick to do and it works, this is not exactly a good advice to simply add using namespace std; at the top of your code. For detailed correct approach, please read the answers to this related SO question.

edited Aug 19 '19 at 18:09

displayName

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answered Mar 03 '13 at 14:08

zbigniewcebula

1,610
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17

Such [bad advice](http://stackoverflow.com/questions/1452721/why-is-using-namespace-std-considered-bad-practice). – juanchopanza Dec 15 '15 at 22:44
5

I know, I made that answer 2 years ago, but now I know it is good enough for beginner, because it is stupid and hard to explain novice programmer what namespace is. – zbigniewcebula Dec 17 '15 at 00:16
8

I disagree. This is particularly bad for beginners because they can't see the implications. – juanchopanza Dec 17 '15 at 00:26
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I agree with @juanchopanza here. It is much easier to start with a solid foundation and explain what everything does so that they don't have to relearn the concepts of something that they thought they already have taken care of – Crutchcorn Feb 04 '16 at 03:40
1

tl;dr "using std::cout;" – NicoKowe Nov 30 '21 at 21:10

score 44 · Answer 2 · answered Mar 03 '13 at 12:47

44

Use std::cout, since cout is defined within the std namespace. Alternatively, add a using std::cout; directive.

answered Mar 03 '13 at 12:47

Andy Prowl

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'cout' was not declared in this scope

2 Answers2