Question

I can’t understand why this works:

#include <iostream>
using namespace std;

int main(){
     signed long int count = 1;

     //...

     count++;

     return 0;
}

And yet if I move the identifier declaration (limit) to the start of the script (just after the using namespace), it fails to compile with the error “count undeclared (first use in this function)” – highlighting the line ‘count++;’.

Alternatively, Codepad results in the following error:

In function 'int main()':
Line 16: error: reference to 'count' is ambiguous
compilation terminated due to -Wfatal-errors.

Thanks,

Will.

Answer 1

You probably have a collision between your count variable and std::count.
You should not use using namespace std as this places everything from the standard library into the global namespace and names will soon collide.

Use specific using lines such as using std::cin; instead.