Chapter 10, Problem 1RQE

Explanation of Solution

“cctype” header file:

The “cctype” header file is used to declare a set of function to categorize the individual characters in C++. The functions in that header file test a single character argument and return either true or false.

The “isalpha” and “isdigit” functions must need “cctype” header file for testing the character argument.

isalpha – check the given letter is alphabet or not

isdigit – check the given letter is digit or not.

isalpha:

If the argument is the letter either uppercase or lowercase, it return true otherwise it return false.

Example:

Consider the example of “isalpha” is as follows:

//declare and initialize the value to the variable

char c = 'a';

//check the condition

if (isalpha (c))

{

//display the output

cout << "This is a letter";

}

Here, the “c” variable holds the value of “a”. The above “if” condition is used to check if the variable “c” is an alphabet by using “isalpha” character function.

isdigit:

If the argument is a digit, it return true otherwise it return false.

Example:

Consider the example of “isdigit” is as follows:

//declare and initialize the value to the variable

char c = '0';

//check the condition

if ( isdigit (c))

{

//display the output

cout << "This is a digit";

}

Here, the “c” variable holds the value of “0”. The above “if” condition is used to check if the variable “c” is a digit by using “isdigit” character function.

Therefore, the “cctype” header file is used to test a single character argument for “isalpha” and “isdigit” function.