Question

I’m getting the error

error: 'INT32_MAX' was not declared in this scope

But I have already included

#include <stdint.h>

I am compiling this on (g++ (GCC) 4.1.2 20080704 (Red Hat 4.1.2-44) with the command

g++ -m64 -O3 blah.cpp

Do I need to do anything else to get this to compile? or is there another C++ way to get the constant “INT32_MAX“?

Thanks and let me know if anything is unclear!

Answer 1

 #include <cstdint> //or <stdint.h>
 #include <limits>

 std::numeric_limits<std::int32_t>::max();

Note that <cstdint> is a C++11 header and <stdint.h> is a C header, included for compatibility with C standard library.

Following code works, since C++11.

#include <iostream>
#include <limits>
#include <cstdint>

struct X 
{ 
    static constexpr std::int32_t i = std::numeric_limits<std::int32_t>::max(); 
};

int main()
{
    switch(std::numeric_limits<std::int32_t>::max()) { 
       case std::numeric_limits<std::int32_t>::max():
           std::cout << "this code works thanks to constexpr\n";
           break;
    }
    return EXIT_SUCCESS;
}

http://coliru.stacked-crooked.com/a/4a33984ede3f2f7e