Question

Write C++ statements to accomplish each of the following: a) In one statement, assign the sum of the current value of \(x\) and \(y\) to \(z\) and postincrement the value of \(x\) b) Determine whether the value of the variable count is greater than \(10 .\) If it is, print "Count is greater than \(10 . "\) c) Predecrement the variable \(x\) by \(1,\) then subtract it from the variable total. d) Calculate the remainder after \(q\) is divided by divisor and assign the result to q. Write this statement two different ways.

Short answer

a) z = x++ + y; b) if (count > 10) {cout << 'Count is greater than 10.';} c) total -= --x; d) q %= divisor; or q = q % divisor;

Step-by-step solution

Assigning the Sum to z and Postincrement x

Use the assignment operator to add the current value of x to y and assign the result to z. Then postincrement x by using the increment operator (++) after the variable.

Conditional Printing for count

Use an if statement to check whether count is greater than 10. If the condition is true, use cout to print the specified message.

Predecrement x and Subtract from total

Predecrement x by using the decrement operator (--) before the variable to decrement it before the operation. Then subtract the new value of x from total.

Calculate Remainder Using Modulus Operator

Use the modulus operator (%) to calculate the remainder when q is divided by divisor. Assign the result back to q.

Alternate Way to Calculate Remainder

Use the modulus assignment operator (%=) as an alternative way to calculate the remainder and assign it to q.

Key concepts

Postincrement Operator

The postincrement operator in C++ is a very useful tool when you want to increase the value of a variable by one but you need to use its current value before the increment. Let's look at how this operator works using the variable x. Imagine x has an initial value of 5, if you write x++, what happens is that x will be used in the context where it appears as 5, but immediately after that expression is evaluated, its value will increase to 6. This is very handy in loops, array processing, or when assigning and updating a value in a single step, as shown in the problem exercise where z gets the sum of x and y, then x is increased by 1 for the next operation.

In practice, the postincrement operator allows you to write concise and readable code that both performs an action and prepares the variable for its next use.

Conditional Statements

Conditional statements are the bread and butter of decision-making in programming. In C++, if statements allow you to branch your code based on whether a condition is true or false. Take the example from the exercise where the program must determine if count is greater than 10. The syntax is straightforward: if (count > 10). If the condition is true, the code inside the braces immediately following the if statement will execute, such as printing a message to the console.

If statements can also be nested and combined with else clauses to handle multiple conditions, enabling complex logical pathways that allow software to make decisions and respond to different scenarios.

Predecrement Operator

The predecrement operator is used to decrease the value of a variable by one before the variable is used in an expression. This is in contrast to the postdecrement operator, which decreases the value of the variable after the expression is evaluated. When you write --x, the variable x is decreased by one, and then the resulting value is used in whatever operation comes next. In the context of the exercise, the new, decremented value of x is immediately used in a subtraction from total.

Predecrement can be especially effective in loops or when you need to adjust an index or counter before using it, ensuring that the operation uses the updated value of the variable.

Modulus Operator

The modulus operator, denoted as %, is used to find the remainder of the division of two integers in C++. For example, 7 % 3 would evaluate to 1, because 7 divided by 3 is 2 with a remainder of 1. This operator is extremely helpful in programming when you need to perform periodic tasks or determine if a number is even or odd among other use cases.

In the exercise, finding the remainder of q divided by divisor is done using the modulus operator. Additionally, the modulus assignment operator %= provides a shorthand method to update a variable with the modulus outcome, streamlining the code and avoiding redundancy. By understanding the usage of the modulus operator, you can effectively handle calculations that require modular arithmetic.