f$.$ Write a $C$ program that removes characters in a string except alphabets $($Assume

English alphabet is used: $a-z$ and A$-$Z$).$ You cannot use string.h library for this exercise.

A sample run would be as follows:

Please enter your string: hello$-/$world

Helloworld

Your program needs to have the following functions:

is$\_$alphabet $()$ : This function will take a character and returns true if it is an

English alphabet character $(a-z$ or A$-$Z$)$ and returns false if it is not. You need to

decide about the input. Add comment for his function and explain the input

and output.

clean$\_$string$()$: This function will remove the characters that are not

alphabet characters in a given string. You need to decide about the input

and return here. Add comment for his function and explain the input and

output.

You need to ask user to enter a string in the main and then make use of

clean$\_$string$()$ function which makes use of is$\_$alphabet$()$ to clean the string.

You will then display the cleaned string in the main.