[따배씨] 15.5 2의 보수 표현법 확인해보기

[따배씨] 15.5 2의 보수 표현법 확인해보기

따배씨 - 따라하며 배우는 C언어

15강 비트 다루기

15.5 2의 보수 2's Complement 표현법 확인해보기

#include <stdio.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>


void print_binary(const char num);
int main()
{
    /*
        Signed Integers
     
        - Sign-magnitude representation
        00000001 is 1 and 10000001 is -1
        00000000 is +0, 10000000 is -0
        Two zeros +0, -0, from -127 to +127
     
        - One's complement method
        To reverse the sign, invert each bit.
        00000001 is 1 and 11111110 is -1.
        11111111 is -0
        from -127 to +127
     */
    
    print_binary(127);
  	// Decimal 127 	== Bianry 01111111
    print_binary(-127);
  	// Decimal -127 	== Bianry 10000001
    print_binary(~127 + 1);
  	// Decimal -127 	== Bianry 10000001
  
    print_binary(12);
  	// Decimal  12 	== Bianry 00001100
    print_binary(-12);
  	// Decimal -12 	== Bianry 11110100
    print_binary(~12 + 1);
  	// Decimal -12 	== Bianry 11110100
    
    return  0;
}

void print_binary(const char num)
{
    printf("Decimal %3d \t== Bianry ", num);
    
    const size_t bits = sizeof(num) * 8;
    
    for (size_t i = 0; i < bits; i++)
    {
        const char mask = (char)pow((double)2, (double)(bits - 1 - i));
        
        if ((num & mask) == mask)
            printf("%d", 1);
        else
            printf("%d", 0);
    }
    printf("\n");
    
}