Which of the following function is used to find the first occurrence of a given

Which of the following function is used to find the first occurrence of a given string in another string?

2) What is the output of this C code?

#include <stdio.h>
     int main()
     {
         char *str = "hello, world\n";
         printf("%d", strlen(str));
       }

3) If the two strings are identical, then strcmp() function returns

4) What is the output of this C code?

#include <stdio.h>
     int main()
     {
         char str[11] = "hello";
         char *str1 = "world";
         strcat(str, str1);
         printf("%s %d", str, str[10]);
     }

5) What will be the output of the program ?

 #include<stdio.h>
 #include<string.h>
 int main()
 {
     char str[] = "Study 2 Online\0 C Language MCQ\0";
     printf("%s\n", str);
     return 0;
 }