math.h and cmath problem

[zuwaka]

I've been trying to use math.h in one of my programs, but nothing's working. I'm using VC++ 2008. This simple code fails.

#include <iostream>
#include <math.h>

int main()
{
    std::cout << sqrt(9);
    return 0;
}

This reports:

c:\documents and settings\shane\desktop\messing around\main.cpp(6) : error C3861: 'sqrt': identifier not found

This also fails:

#include <iostream>
#include <cmath>

int main()
{
    std::cout << std::sqrt(9);
    return 0;
}

It reports over one hundred errors.

[Athar]

If your compiler does not provide overloaded functions for integral types (it isn't required to), you'll have to explicitly cast to another type, namely one of these three:

http://www.cplusplus.com/reference/clibrary/cmath/sqrt/

...or just provide a double literal in the first place:
std::sqrt(9.0)

[zuwaka]

That's not the problem, the problem is that for some reason the sqrt() (and sin() and cos()) functions don't seem to be defined. The funny thing is, I've used sqrt() before and it worked.

[Athar]

So perhaps you should post these "over one hundred errors".

[zuwaka]

Mkay, here they are.

c:\program files\microsoft visual studio 9.0\vc\include\cmath(21) : error C2039: 'acosf' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(21) : error C2873: 'acosf' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(21) : error C2039: 'asinf' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(21) : error C2873: 'asinf' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(22) : error C2039: 'atanf' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(22) : error C2873: 'atanf' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(22) : error C2039: 'atan2f' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(22) : error C2873: 'atan2f' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(22) : error C2039: 'ceilf' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(22) : error C2873: 'ceilf' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(23) : error C2039: 'cosf' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(23) : error C2873: 'cosf' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(23) : error C2039: 'coshf' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(23) : error C2873: 'coshf' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(23) : error C2039: 'expf' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(23) : error C2873: 'expf' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(24) : error C2039: 'fabsf' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(24) : error C2873: 'fabsf' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(24) : error C2039: 'floorf' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(24) : error C2873: 'floorf' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(24) : error C2039: 'fmodf' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(24) : error C2873: 'fmodf' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(25) : error C2039: 'frexpf' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(25) : error C2873: 'frexpf' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(25) : error C2039: 'ldexpf' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(25) : error C2873: 'ldexpf' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(25) : error C2039: 'logf' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(25) : error C2873: 'logf' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(26) : error C2039: 'log10f' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(26) : error C2873: 'log10f' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(26) : error C2039: 'modff' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(26) : error C2873: 'modff' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(26) : error C2039: 'powf' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(26) : error C2873: 'powf' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(27) : error C2039: 'sinf' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(27) : error C2873: 'sinf' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(27) : error C2039: 'sinhf' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(27) : error C2873: 'sinhf' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(27) : error C2039: 'sqrtf' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(27) : error C2873: 'sqrtf' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(28) : error C2039: 'tanf' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(28) : error C2873: 'tanf' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(28) : error C2039: 'tanhf' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(28) : error C2873: 'tanhf' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(30) : error C2039: 'acosl' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(30) : error C2873: 'acosl' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(30) : error C2039: 'asinl' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(30) : error C2873: 'asinl' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(31) : error C2039: 'atanl' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(31) : error C2873: 'atanl' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(31) : error C2039: 'atan2l' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(31) : error C2873: 'atan2l' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(31) : error C2039: 'ceill' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(31) : error C2873: 'ceill' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(32) : error C2039: 'cosl' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(32) : error C2873: 'cosl' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(32) : error C2039: 'coshl' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(32) : error C2873: 'coshl' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(32) : error C2039: 'expl' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(32) : error C2873: 'expl' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(33) : error C2039: 'fabsl' : is not a member of '`global namespace''

[zuwaka]

c:\program files\microsoft visual studio 9.0\vc\include\cmath(33) : error C2873: 'fabsl' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(33) : error C2039: 'floorl' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(33) : error C2873: 'floorl' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(33) : error C2039: 'fmodl' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(33) : error C2873: 'fmodl' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(34) : error C2039: 'frexpl' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(34) : error C2873: 'frexpl' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(34) : error C2039: 'ldexpl' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(34) : error C2873: 'ldexpl' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(34) : error C2039: 'logl' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(34) : error C2873: 'logl' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(35) : error C2039: 'log10l' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(35) : error C2873: 'log10l' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(35) : error C2039: 'modfl' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(35) : error C2873: 'modfl' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(35) : error C2039: 'powl' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(35) : error C2873: 'powl' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(36) : error C2039: 'sinl' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(36) : error C2873: 'sinl' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(36) : error C2039: 'sinhl' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(36) : error C2873: 'sinhl' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(36) : error C2039: 'sqrtl' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(36) : error C2873: 'sqrtl' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(37) : error C2039: 'tanl' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(37) : error C2873: 'tanl' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(37) : error C2039: 'tanhl' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(37) : error C2873: 'tanhl' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(41) : error C2039: 'acos' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(41) : error C2873: 'acos' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(41) : error C2039: 'asin' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(41) : error C2873: 'asin' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(42) : error C2039: 'atan' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(42) : error C2873: 'atan' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(42) : error C2039: 'atan2' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(42) : error C2873: 'atan2' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(42) : error C2039: 'ceil' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(42) : error C2873: 'ceil' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(43) : error C2039: 'cos' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(43) : error C2873: 'cos' : symbol cannot be used in a using-declaration
c:\program files\microsoft visual studio 9.0\vc\include\cmath(43) : error C2039: 'cosh' : is not a member of '`global namespace''
c:\program files\microsoft visual studio 9.0\vc\include\cmath(43) : fatal error C1003: error count exceeds 100; stopping compilation

[Skillless]

Are you sure all these functions are in namespace std?

(because you seem to be using std::sqrt, and in the example in http://www.cplusplus.com/reference/clibrary/cmath/sqrt/ it uses sqrt without std::)

[zuwaka]

They're supposed to be in namespace std.

[zuwaka]

I upgraded to VC++ 2010, and the problem seems to be solved.