#include <stdio.h>
#include <stdlib.h>
#define MAX_STRING_LENGHT 256

int numsub(char *str, char *sub)
{
    int num = 0;
    char *ptrstr;
    char *ptrsub;
    while (*str)
    {
        if (*str == *sub)
        {
            int trigger = 1;
            ptrstr = str;
            ptrsub = sub;
            while (*ptrstr &&*ptrsub)
            {
                trigger = trigger && (*ptrstr == *ptrsub);
                ptrstr++;
                ptrsub++;
            }
            if (trigger)
            {
                num++;
            }
        }
        str++;
    }
    return num;
}

char *strstr(char* str, char* sub)
{
    char *ptrstr;
    char *ptrsub;
    while (*str)
    {
        if (*str == *sub)
        {
            int trigger = 1;
            ptrstr = str;
            ptrsub = sub;
            while (*ptrstr &&*ptrsub)
            {
                trigger = trigger && (*ptrstr == *ptrsub);
                ptrstr++;
                ptrsub++;
            }
            if (trigger)
            {
                return str;
            }
        }
        str++;
    }
    return NULL;
}

int str_len(char *str)
{
    int len = 0;
    while (*str)
    {
        len++;
        str++;
    }
    return len;
}

char *str_ncpy(char *toHere, char *fromHere, int n)
{
    char* buffer2 = (char*)malloc(MAX_STRING_LENGHT);
    int i;
    toHere = buffer2;
    if (n>str_len(fromHere))
    {
        n = str_len(fromHere);
    }
    for (i = 0; i<n; i++)
    {
        toHere[i] = fromHere[i];
        //printf("%c\n", toHere[i]);
        //printf("%d\n", i);
    }
    toHere[i] = '\0';
    return toHere;
}

char *str_ncat(char *toHere, char *fromHere, int n)
{
    int l = str_len(toHere), k, i;
    i=l;
    printf("i(1)=%d\n",i);
    for (i = l, k = 0; i<l + n; i++, k++)
    {
        //printf("%c\n", toHere[i]);
        toHere[i] = fromHere[k];
        //printf("%c\n",toHere[i]);
    }
    toHere[i] = '\0';
    return toHere;
}

char* findandinsert(char* str, char* sub, char* rep)
{
    int i, l;
    l = numsub(str, sub);
    char* buffer = (char*)malloc(MAX_STRING_LENGHT);
    char* buffer1 = (char*)malloc(MAX_STRING_LENGHT);
    char* buffer2 = (char*)malloc(MAX_STRING_LENGHT);
    buffer1 = str;
    buffer2 = str_ncpy(buffer2,buffer1,0);
    if (l == 0)
    {
        return str;
    }
    for (i = 0; i < l; i++)
    {
        buffer1 = str;
        printf("buffer1: %s\n", buffer1);
        buffer = str_ncpy(buffer, buffer1, str_len(str) - str_len(strstr(str, sub)));
        printf("buffer:  %s\n", buffer);
        buffer = str_ncat(buffer, rep, str_len(rep));
        printf("buffer:  %s\n", buffer);
        buffer2 = str_ncat(buffer2, buffer , str_len(buffer));
        printf("buffer2: %s\n", buffer2);

        str = strstr(str, sub) + str_len(sub);
        printf("str:     %s\n\n", str);


    }
    buffer2 = str_ncat(buffer2, str, str_len(str));
    return buffer2;
}

int main()
{
    int i, l;
    char* str = (char*)malloc(MAX_STRING_LENGHT);
    char* sub = (char*)malloc(MAX_STRING_LENGHT);
    char* rep = (char*)malloc(MAX_STRING_LENGHT);
    str = "aaaabcdebcfgbc";
    sub = "bc";
    rep = "9";
    l = numsub(str, sub);
    printf("INITIAL STR: %s\n", str);
    printf("SUBSTR:      %s\n", sub);
    printf("REPSTR:      %s\n\n", rep);
    printf("FINAL STR:   %s\n", findandinsert(str, sub, rep));
    return 0;
}