Program to Concatenate Two Strings

#include<stdio.h>

int main() {
   
   char str1[100] = "PrepInsta ";
   char str2[100] = "is one of the best for preparing placement ";
   char str3[100] =  " and for techincal skill";
   // finding length of string 1
   int length =0;
   while(str1[length] != '\0'){
       length++;
   }
   // adding second string to first string
   for(int i=0; str2[i] != '\0'; i++){
       str1[length] = str2[i];
       length++;
   }
   // adding third string into first string
   for(int i=0; str3[i] != '0'; i++){
       str1[length] = str3[i];
       length++;
   }
   str1[length] = '\0';
   puts(str1);

    return 0;
}