Error in compiling .cpp file

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1

I get this error,

defaults.cpp: In member function �int Defaults::GetIntDefault(const std::string&)�:
defaults.cpp:68: error: �atoi� was not declared in this scope
defaults.cpp: In member function �real_t Defaults::GetRealDefault(const std::string&)�:
defaults.cpp:76: error: �atof� was not declared in this scope
defaults.cpp: At global scope:
defaults.cpp:8: warning: �rcsid� defined but not used
make: *** [defaults.o] Error 1

when attempting to compile this code:

int
Defaults::GetIntDefault(  const string& defaultName ) throw ( DfltsErr )
{
    int val;
    val = atoi( GetStringDefault( defaultName ).c_str() );
    return val;
}

real_t
Defaults::GetRealDefault(  const string& defaultName ) throw ( DfltsErr )
{
    real_t val;
    val = atof( GetStringDefault( defaultName).c_str() );
    return val;
}

The file has the following headers (I don't know if they are relevant to this problem):

#include <ctype.h>
#include <fstream>
#include <sstream>
#include <cstring>
#include "msgdlg.h"
#include "defaults.h"
2

You need cstdlib - the header where those functions are defined.