Question

gcc 4.6.1 c89

I have a string that I need parse. The string is sdp information. I am trying to seperate each of the elements into seperate strings.

Basically the string would contain some thing like this:

v=0 o=sip_user IN 10230 22472 IP4 10.10.10.44 s=SIP_CALL c=IN IP4 10.10.10.44 m=audio 49152 RTP/AVP 0 8 a=rtpmap:0 PCMU/8000 a=rtpmap:8 PCMA/8000

And I would like to seperate them into different strings. So this needs to be broken down into seperate strings.

str1 v=0 
str2 o=sip_user IN 10230 22472 IP4 10.10.10.44 
str3 s=SIP_CALL 
str4 c=IN IP4 10.10.10.44 
str5 m=audio 49152 RTP/AVP 0 8 
str6 a=rtpmap:0 PCMU/8000 
str7 a=rtpmap:8 PCMA/8000

I was trying to do something like this as a start. But even though it finds the v= I need to find when the next line will start.

char *str_v = NULL  
str_v = strstr(sdp_string, "v=");

if(str_v != NULL) {
    printf("found line: [ %s ]", str_v);
}

Many thanks for any suggestions,

Answer 1

First, find the beginnings of all substrings (parts array below), then null terminate each of them. This is just to show how simple it can be to parse if the format is fixed.

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

int main() {
        char input[] = "v=0 o=sip_user IN 10230 22472 IP4 10.10.10.44 s=SIP_CALL c=IN IP4 10.10.10.44 m=audio 49152 RTP/AVP 0 8 a=rtpmap:0 PCMU/8000 a=rtpmap:8 PCMA/8000";
        char *parts[16] = {0};
        int top = 0;
        int i;
        char *s = input;
        while (top < 15 && (s = strchr(s, '='))) {   /* find each = and save a pointer to before it */
                parts[top++] = s-1;
                s++;
        }
        for (i = 1; parts[i]; i++)
                parts[i][-1] = '\0';  /* null terminate each part */
        for (i = 0; parts[i]; i++)
                printf("%s\n", parts[i]);
        return 0;
}