CODEWITHSUNDEEP
ctype-conversion
harry77
harry77

Reputation: 117

convert a string to hex integer in C

I have the following C string 

"72e4247d3c91f424c62d909d7c1553a5"

It consists of 32 hex digits. It is an array with 4 integers in hex. How can I get back the numbers in form of integers from this array?

Upvotes: 1

Views: 297

Answers (2)

Fred Foo
Fred Foo

Reputation: 363487

You'll have to parse the four 32-bit/8 hex digit chunks separately. The easiest way to do that is

#include <stdint.h>
#include <stdlib.h>
#include <string.h>

void parse_hex4(char const *str, uint32_t num[4])
{
    char buf[9];  // 8 hex digits + NUL

    buf[8] = '\0';
    for (int i=0; i<4; i++) {
        memcpy(buf, str + i * 8, 8);
        num[i] = strtoul(buf, NULL, 16);
    }
}

This assumes str is zero-padded to be exactly 32 characters long and it does no input validation. If you're using the compiler from Redmond that is stuck in the 1980, use unsigned long instead of uint32_t.

Upvotes: 4

wizard
wizard

Reputation: 1544

Have you tried strtol ? 

int val = (int) strtol (hex_string, NULL, 16);

Repeat on substrings if it is a flattened array.

Regards

Upvotes: 0

Related Questions