How can I convert hexadecimal bytes {0x00, 0x03, 0x9e, 0x40} to int for calculation in c?

Question

I am having issues converting hexadecimal bytes to int so as to calculate the sum.

I have this hexadecimal bytes in a char array but I am having issues converting them to decimal(int) and summing all of them. here is some lines of code:

int main() {

  char recv[4] = {0x00, 0x03, 0x9e, 0x40};

  int d1 = recv[0] * 256;
  int d2 = recv[1] * 256;
  int d3 = recv[2] * 256;
  int d4 = recv[3] * 1;

  int dt = d1 + d2 + d3 + d4; 

  printf("d1: %d\n", d1);
  printf("d2: %d\n", d2);
  printf("d3: %d\n", d3);
  printf("d4: %d\n", d4);

  printf("sum is: %d\n", dt);


  return 0;

This is the result I am getting:

d1: 0
d2: 768
d3: -25088
d4: 64
sum is: -24256

use `unsigned char`. Also your multiplication is off, it should be `1677216`, `65536` and `256`. And lastly you should use bitshifts instead. — Antti Haapala -- Слава Україні, Aug 28 '19 at 11:21

score 0 · Accepted Answer · answered Aug 28 '19 at 11:32

0

#include <stdio.h>

int main(void)
{
    char recv[4] = {0x00, 0x03, 0x9e, 0x40};
    unsigned int result;

    result = ((unsigned char)recv[0] << 24) | 
             ((unsigned char)recv[1] << 16) |
             ((unsigned char)recv[2] <<  8) |
             ((unsigned char)recv[3] <<  0);

    printf("0x%08X\n", result);

    return 0;
}

Output

(link)

Success #stdin #stdout 0s 4568KB
0x00039E40

answered Aug 28 '19 at 11:32

abelenky

63,815
23
109
159

Explanation?... – S.S. Anne Aug 28 '19 at 15:23
You can still [edit your answer](https://stackoverflow.com/posts/57691429/edit) and provide more details. – S.S. Anne Aug 28 '19 at 15:31

How can I convert hexadecimal bytes {0x00, 0x03, 0x9e, 0x40} to int for calculation in c?

1 Answers1

Output