1. Write a program to determine the character that occurs most in a user-input string. 2. Write a program that uses the str_insert(s, s1, s2) function to locate a substring s1 in string s and insert...

1. Write a program to determine the character that occurs most in a user-input string.

2. Write a program that uses the str_insert(s, s1, s2) function to locate a substring s1 in string s and insert a substring s2 before s1. The function must return a pointer to s if the insertion is successful, or NULL otherwise.

3. Write a program that splits a string on any of the delimiters stored in the string “ |:;” (includes a space), and saves the words in a 2D char array. The program must accept a line of text from keyboard input and print each word on a separate line.