How to make int from char[4]? (in C)

c, casting

Solution

This works, but gives different results depending on the size of int, endian and so on..

#include <stdio.h>

int main(int argc, char *argv[])
{

    char a[4];
    a[0] = 0x76;
    a[1] = 0x58;
    a[2] = 0x02;
    a[3] = 0x00;
    printf("%d\n", *((int*)a));
    return 0;
}

This is cleaner but you still have endian/size problems.

#include <stdio.h>

typedef union {
    char c[4];
    int i;
} raw_int;

int main(int argc, char *argv[])
{

    raw_int i;
    i.c[0] = 0x76;
    i.c[1] = 0x58;
    i.c[2] = 0x02;
    i.c[3] = 0x00;
    printf("%d\n", i.i);
    return 0;
}

To force a certain endianness, build the `int` manually:

int i = (0x00 << 24) | (0x02 <<< 16) | (0x58 << 8) | (0x76);
printf("%d\n", i);

Problem

Original source

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