C上的浮点表示错误

Question

So I want to verify the hexadecimal representation of the number 1.0 in Language C, below are my codes:

int main(int argc, char **argv)
{
    void showBytes(unsigned char * p,int size){
        int i;
        for (i=0;i<size;i++){
            printf("%.2x",p[i]);
        }
    }

    float f;
    f=1.0;
    showBytes((unsigned char *)&f,sizeof(f));
    return 0;
}

When I build and run my program, I get 39300000, which is not the correct representation of 1.0(00003039). Can any one explain to me why I get this incorrect value? Thanks!!!

Answer 1

This is an endianness mis-match. You are displaying the value using one endianness convention, but your expected value uses the other convention.

Endianness is a well-known issue for integer data types, but it is perhaps less well known endianness also affects floating point representation.