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 will be the output of the following program?

void main()
 {
       char str1[] = "abcd";
       char str2[] = "abcd";
       if(str1==str2)
             printf("Equal");
       else
             printf("Unequal");
 }

3) What is the output of this C code?

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

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

5) The library function used to find the last occurrence of a character in a string is