Index of nth Occurrence of the string

Question

How do I find the index of nth occurrence of the given string in a line? I need this to take a substring from that index. Is that possible through any functions in c++?

Answer 1

You can use the following function

#include <string.h>

int strpos(char *haystack, char *needle, int nth)
{
    char *res = haystack;
    for(int i = 1; i <= nth; i++)
    {
        res = strstr(res, needle);
        if (!res)
            return -1;
        else if(i != nth)
            res++;
    }
    return res - haystack;
}

Returns -1 if it can not find the nth occurrence.