string joiner 1by1 *ptr

#include <stdio.h>
void func(char* arr, char* arr1, char* arr2) {
    char* ptr = arr; char* ptr1 = arr1; char* ptr2 = arr2;
    while (*ptr != '\0' && *ptr1 != '\0') {

        *ptr2 = *ptr;
        ptr2++; ptr++;

        *ptr2 = *ptr1;
        ptr2++; ptr1++;
    }


    while (*ptr != '\0')
    {
        //printf("%c", *ptr);
        //ptr++;
        *ptr2 = *ptr;
        ptr++;
        ptr2++;


    }
    while (*ptr1 != '\0')
    {
        //printf("%c", *ptr1);
        //ptr1++;
        *ptr2 = *ptr1;
        ptr1++;
        ptr2++;
    }
    while (*ptr1 != '\0')
    {
        //printf("%c", *ptr1);
        //ptr1++;
        *ptr2 = *ptr1;
        ptr1++;
        ptr2++;
    }
    *ptr2 = '\0';
    printf("\n%s", arr2);
}


int main() {
    char arr[] = "hello_cunt";
    char arr1[] = "world";
    char arr2[100];
    int size1 = 0, size2 = 0;
    for (int i = 0; arr[i] != '\0'; i++) {
        size1++;
    }
    printf("size1:%d\n", size1);
    for (int i = 0; arr1[i] != '\0'; i++) {
        size2++;
    }
    printf("size2:%d\n", size2);
    func(arr, arr1, arr2);


    return 0;
}