Minus zero ≠ zero in C++ (and C and other C-based languages)

gistfile1.cpp

#include <iostream>
#include <iomanip>
#include <cstdint>
#include <cstring>

using namespace std;

typedef float fltp;

int main(void){
	fltp zero=0,mzero=-zero;
	uint8_t zero_bytes[sizeof(fltp)],mzero_bytes[sizeof(fltp)];

	memcpy(zero_bytes,&zero,sizeof(fltp));
	memcpy(mzero_bytes,&mzero,sizeof(fltp));

	cout<<" 0: "; for(int i=0;i<sizeof(fltp);i++)cout<<hex<<(int) zero_bytes[i]<<' '; cout<<endl;
	// ->  0: 0 0 0 0

	cout<<"-0: "; for(int i=0;i<sizeof(fltp);i++)cout<<hex<<(int)mzero_bytes[i]<<' '; cout<<endl;
	// -> -0: 0 0 0 80
	return 0;
}