OS question: Please answer and explain the answer. Thank you

7. Complete the following program by writing the mystrchr function so that it would compile/run. This function returns a pointer to the first occurrence of the character c in the string str, or NULL if the character is not found. This should be done without using the library function strchr. For example the following program would have an output of String after |.| is - Tandon | 1 #include stca.h> #include 4 char nystrchr(const char "str, int c); 6int nain Const char str[]NYU.Tandon 8 const char ch 9 char 'ret 18 ret mystrchr str, ch) 11 printf( String after c is -sI'n", ch, ret+1) 12 return(a) 13 14 15 char strchr(canst char 'str, int e)