Question

Write four different \(C++\) statements that each add 1 to integer variable \(x.\)

Short answer

x++; or ++x; or x += 1; or x = x + 1;

Step-by-step solution

Statement Using Postfix Increment Operator

Use the postfix increment operator to increase the value of the variable by 1. In code: x++;. This statement adds 1 to x and then yields the original value of x.

Statement Using Prefix Increment Operator

Use the prefix increment operator to increase the value of the variable by 1 before its value is used in expressions. In code: ++x;. This statement increases x by 1 and immediately yields the new value.

Statement Using Addition Assignment Operator

Use the addition assignment operator to add a value to the variable. In code: x += 1;. This adds 1 directly to the current value of x.

Statement Using Basic Addition

Perform a basic addition to add 1 to the variable and update its value. In code: x = x + 1;. This takes the current value of x, adds 1, and then assigns the result back to x.

Key concepts

Postfix Increment Operator

Understanding the postfix increment operator is essential when learning C++. This operator, represented by two plus signs following a variable, as in x++, is used to increase the value of the variable by 1 after its current value has been used. Imagine you're counting apples in a basket, and after counting each apple, you mark it; this is similar to how the postfix operator works—you use the apple (variable), then mark it (increment).

Here's how you might see it in action:

• int x = 5;
• int y = x++;
• // Now, x is 6 and y is 5

The key point to remember is that the original value of x is used in any expressions or assignments before x itself is incremented.

Prefix Increment Operator

The prefix increment operator is another way to add 1 to a variable in C++. Unlike the postfix version, the prefix increment operator, denoted with two plus signs before a variable, as in ++x, increments the variable's value before it's used anywhere else. It's like preparing all of your apples by washing them before putting them into the basket.

Consider this example:

• int x = 5;
• int y = ++x;
• // x is now 6, and y is also 6

This behavior has implications when the increment is part of a larger expression. It ensures that you're working with the updated value right away.

Addition Assignment Operator

If you're looking to increase a variable's value directly and concisely, the addition assignment operator += is your tool of choice. This operator combines addition and assignment in one sleek motion. For example, the statement x += 1 essentially tells the computer, 'Take the current value of x, add 1 to it, and then make this new sum the value of x.'

It's like saying, 'I have these many apples, I'm getting one more, and that's my new total.' This operator simplifies code and eliminates the need to write the variable out twice, as compared to x = x + 1.

Basic Addition in C++

The most straightforward way to increase a value in C++ is with basic addition. To add 1 to a variable, you simply take its current value, add 1, and then update the variable with the new value using the equals operator. In code, this looks like x = x + 1.

This is equivalent to a one-step process where you hold a certain number of apples, say 'I have one more,' and count them together to find your new total. While this approach is clear and intuitive, especially for those new to programming, it's often substituted with the more concise increment operators or the addition assignment operator in practice.