an function to index into string

str_index.c

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

char* strindex(char* src,int start, int end) {
    int len = end - start;
    char* dst = malloc(len + 2);
    for (int i = 0; i < (end - start) + 1; i++)
    	dst[i] = src[i + start];
    dst[len + 1] = 0;
    return dst;
}

int main() {
	char* x = "0123456789";
	char* substring = strindex(x,1,3);
	printf("%s,%s\n", x, substring);
	free(substring);
	return 0;
}