how to convert char array to int in C language

Question

i've some troubels here, i want to convert this char array

char IP[]="2001:2AB1:30A1:2000:1000:ABC1"

to 4 int key1,key2,key3,key4 with 
key1=2001
key2=2AB1
key3=30A1
key4=2000:1000:ABC1

im working in C language.

Thank you

Also, it doesn't seem you have googled `"C convert string to integer"`, for which you should feel bad. — , Jun 15 '13 at 20:12
How is key4 supposed to be converted to an int? What do you expect? — friol, Jun 15 '13 at 20:13
You'll have to do some work to divide up the input, but generally `strtol` is a useful basis. See http://stackoverflow.com/q/10324/2246674 for a variety of methods. (They'll need some adaptation). Also, `30A1` is an *invalid* C base-10 number literal (what is "A" to a decimal?) while `0x30A1` is a base-16 number literal that evaluates to 12449. — user2246674, Jun 15 '13 at 20:18
i'm sorry ! i made a mistake ! input is char IP[]="2001:2AB1:30A1:2000:1000:ABC1" & output key1=2001 key2=2AB1 key3=30A1 key4=20001000ABC1 — Ismael Rachdaoui, Jun 15 '13 at 20:19
i think i have to convert first from hex to decimal then do the procecess — Ismael Rachdaoui, Jun 15 '13 at 20:22

score 2 · Answer 1 · answered Jun 15 '13 at 20:26

2

It looks like you want to convert an IPv6 address to four integers. I'd recommend you leverage existing library functions to accomplish this, if they're available in your environment. Specifically, inet_ntop can convert your string to an struct in6_addr which should be much easier to deal with.

answered Jun 15 '13 at 20:26

Mike Pelley

2,939
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23

yes it's an IPv6 adresse that i want to divide into keys to do some operation in each keys – Ismael Rachdaoui Jun 15 '13 at 20:36

score 0 · Answer 2 · answered Jun 15 '13 at 21:02

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

char *strdelch(char *str, char ch){
    char *from, *to;
    if(NULL==str)return str;

    from=to=str;
    while(*from){
        if(*from != ch)
            *to++ = *from;
        ++from;
    }
    *to = '\0';
    return str;
}

int main(void){
    char IP[]="2001:2AB1:30A1:2000:1000:ABC1";
    int key1,key2,key3;
    int64_t key4;
    char *p = IP;

    key1 = strtol(p, &p, 16);
    key2 = strtol(++p, &p, 16);
    key3 = strtol(++p, &p, 16);
    key4 = strtoll(strdelch(++p, ':'), NULL, 16);
    printf("%04X\n", key1);
    printf("%04X\n", key2);
    printf("%04X\n", key3);
    printf("%012I64X\n", key4);
    return 0;
}

how to convert char array to int in C language

2 Answers2