Question

Assume \(c\) is a char variable. What value does \(c\) hold after each of the following statements executes? Statement \(\quad\) Contents of \(c\) \(c=\) toupper \(\left(' a^{\prime}\right)\) \(c=\) toupper \(\left(' B^{\prime}\right)\) \(c=\) tolower \(\left(' D^{\prime}\right)\) \(c=\) toupper \(\left(' e^{\prime}\right)\)

Short answer

1. c = toupper('a'); 2. c = toupper('B'); 3. c = tolower('D'); 4. c = toupper('e'); Answer: 1. 'A' 2. 'B' 3. 'd' 4. 'E'

Step-by-step solution

Statement 1

First, let's find the value of \(c\) after the given statement executes: $$c = \text{toupper} \left(' a^{\prime}\right)$$ Here, the function toupper() is called with the lowercase character 'a'. The function takes this character and returns its uppercase version 'A'. So, after the statement executes, the value of \(c\) will be 'A'.

Statement 2

Now, let's find the value of \(c\) after the given statement executes: $$c = \text{toupper} \left(' B^{\prime}\right)$$ The input to the function toupper() is the uppercase character 'B'. Since it's already in uppercase, the function returns 'B' unchanged. So, after the statement executes, the value of \(c\) will be 'B'.

Statement 3

Let's find the value of \(c\) after the given statement executes: $$c = \text{tolower} \left(' D^{\prime}\right)$$ Here, the function tolower() is called with the uppercase character 'D'. The function takes this character and returns its lowercase version 'd'. So, after the statement executes, the value of \(c\) will be 'd'.

Statement 4

Finally, let's find the value of \(c\) after the given statement executes: $$c = \text{toupper} \left(' e^{\prime}\right)$$ The input to the function toupper() is the lowercase character 'e'. The function takes this character and returns its uppercase version 'E'. So, after the statement executes, the value of \(c\) will be 'E'.

Key concepts

toupper function

In C++, the `toupper` function is a useful tool for converting characters to uppercase. When you pass a lowercase alphabetical character to `toupper`, it returns the corresponding uppercase character.
For example, consider the function call `toupper('a')`. It takes the character 'a' as an input and returns 'A'.
This function is part of the C++ Standard Library, specifically within the `` header file.

• Only works with standard ASCII characters; non-alphabetic characters remain unchanged.
• Automatically handles the conversion without the need for manual coding logic.
• Can be used in programming tasks where uniform case representation is essential.

To effectively utilize `toupper`, ensure that your program includes the necessary header file with `#include `.

tolower function

The `tolower` function is the counterpart to `toupper`, designed to convert characters to lowercase in C++. It is handy when you need consistency by having all characters in the lowercase form.
Passing an uppercase character to `tolower` returns the lowercase equivalent.
Consider `tolower('D')`, which processes the character 'D' and returns 'd'.

• Part of the C++ Standard Library, under the `` header.
• Does not alter non-alphabetic characters; they remain the same.
• Useful for tasks needing case-insensitive comparisons.

Ensure you include the `` header file to use this function in your program by adding `#include `.

character variables

In C++, a character variable is typically declared using the `char` keyword. This datatype is used to store individual character values, such as letters or symbols.
Each character has a corresponding ASCII value, which is a numerical representation inside a computer.
For example, a character variable can be declared and initialized like this: `char c = 'A';`.

• Typically 1 byte in size, but can vary depending on the system architecture.
• When you manipulate characters, you're often working with their underlying ASCII values.
• Can store any character from the ASCII table, including special characters and spaces.

Character variables are fundamental in text processing and often interact with functions like `toupper` and `tolower` to change their case.

uppercase and lowercase conversion

Converting between uppercase and lowercase is a common task in C++ programming. This is often necessary for standardizing text input and ensuring uniform data processing.
Functions like `toupper` and `tolower` simplify these conversions by handling character cases efficiently.
The conversions rely on ASCII values, where uppercase letters have different numeric values than lowercase letters.

• Uppercase to lowercase conversions subtract a specific value based on the ASCII table.
• Lowercase to uppercase involves adding the same value.
• Automation in conversion reduces programming errors and enhances readability.

To perform these conversions, include the `` library and use the functions to transform individual characters according to your program's needs.