C language/ programming

Write a function that returns the index of character c in string str int index Of(char * str, char c) Write a function that returns the index of substring sub in string str int indexOf(char * str, char sub) Write a function that returns the index of the last occurrence of character c in string str int lastIndexOf(char *str, char c) Write a function that returns the character at position idx in string str char charAt(char *str, int idx) Write a function that returns 1 if string str starts with the string sub, 0 otherwise int startsWith(char *str, char sub) Write a function that returns a new string consisting of the sequence of characters between the ith and jth index in str char substring(char *str, int i. int j)