Split a complex string in C

Question

Ok, so what I need to do is split a string. Here is an example string that I need to split:

test_french_fries

and let's say I want to split the string into two parts, the part before and after:

french

thus I would get a return of something like:

match[1]=[test_]
match[2]=[_fries]

I have tried messing around with strtok() but I have had no success with that. It appears that strtok() splits the string at all delims that are given - so if I were to give it a delim of french, it would separate the string for each character matched - which ISN'T what I want.

I would like to have a delim where I can provide it a str or char* such as "french" and the string be split before and after the string provided.

Are there any other methods besides strtok() that I could possibly try to implement in order to achieve my desired outcome?

I really appreciate any and all help that I receive.

-Patrick

duplicate: http://stackoverflow.com/questions/17250526/split-a-complex-string-using-regex-in-c-sharp — catalyst, Aug 01 '15 at 18:16
There is nothing stopping you re-adding the delimiter after you've split the string up. — cup, Aug 01 '15 at 18:22
You can just find the substring and get the index. so the two strings would be string 1) pos 0 to index; and string 2) will be (index + strlen(delimiter)) to end. — Aritra Chakraborty, Aug 01 '15 at 18:42

Havenard · Accepted Answer · 2015-08-01T21:18:27.003

strtok() can only split using a single symbol as separator (1 character), you can specify multiple separators in the form of a null-terminated string, but they are delt with individualy. To split a string with another string as separator, you will have to write a custom function. The example below works just like strtok(), but uses a null-terminated C string as separator:

#include <stdio.h>

char *strstrtok(char *src, char *sep)
{
    static char *str = NULL;
    if (src) str = src;
    else src = str;

    if (str == NULL)
        return NULL;

    char *next = strstr(str, sep);
    if (next)
    {
        *next = '\0';
        str = next + strlen(sep);
    }
    else
        str = NULL;

    return src;
}

int main(void) {
    char buf[] = "yoursepmamasepissepsosepfatsepsheseptooksepasepspoonseptosepthesepsuperbowl";
    char *token = strstrtok(buf, "sep");
    while (token)
    {
        printf("%s ", token);
        token = strstrtok(NULL, "sep");
    }
    return 0;
}

Notice just like strtok(), this solution is not thread-safe.

See it working on Ideone: http://ideone.com/cjRGgJ

better to use `strtok_r` as the model and take an extra `save` pointer, rather than using a non-reentrant/thread safe static var... — Chris Dodd, Aug 01 '15 at 18:50
Yes, this is perfect. I had just started to write something like this, but yours is exactly what I need. — Hard Tacos, Aug 01 '15 at 18:58

Split a complex string in C

1 Answers1