Question

Assume \(x=4, y=7,\) and \(z=2 .\) What value will be stored in integer variable result by each of the following statements? A) result \(=x+y i\) B) result \(=y * 2\) C) result \(=y / z\)

Short answer

Answer: For Statement A, the value stored in 'result' will be 11. For Statement B, the value stored in 'result' will be 14. For Statement C, the value stored in 'result' will be 3.

Step-by-step solution

Statement A: result = x + y

To find the value stored in 'result' by this statement, we simply add the given values of x and y: result = 4 + 7 = 11 So, for Statement A, the integer variable 'result' will store the value 11.

Statement B: result = y * 2

To find the value stored by this statement, we multiply the given value of y by 2: result = 7 * 2 = 14 So, for Statement B, the integer variable 'result' will store the value 14.

Statement C: result = y / z

To find the value stored by this statement, we divide the given value of y by the given value of z. It is important to remember that 'result' is an integer, so any decimal value will be truncated: result = floor(7 / 2) = 3 So, for Statement C, the integer variable 'result' will store the value 3.

Key concepts

Integer Variables

In C++, integer variables are used to store whole numbers without any fractional part. When you declare a variable as an integer type, such as int, the compiler allocates memory to hold an integer value and treats it accordingly.

For instance, in our exercise, variables x, y, and z are declared as integer types, as well as the variable result. This means that no matter what arithmetic operation is performed, result will ultimately hold an integer value. If an operation involves decimals, the digits after the decimal point are removed, or 'truncated', to fit into the integer variable.

Being able to predict the value of integer variables after various operations is essential in programming because it affects logic and flow control in your code.

Basic Operators in C++

C++ provides a variety of basic operators that you can use to perform arithmetic operations. These are fundamental tools to manipulate data and include addition (+), subtraction (-), multiplication (*), and division (/).

The addition operator adds two operands; for example, result = x + y is adding the values of x and y. Similarly, the multiplication operator multiplies them, as seen in the exercise with result = y * 2. The results of these operations are straightforward when dealing with integer variables; you simply perform the operation as you would with whole numbers.

However, with division, there's an additional consideration, which is especially important when dividing two integers, as it can lead to truncation - a concept that'll be compressed in more depth in the next section.

Truncation in Integer Division

Truncation is a crucial concept when dealing with integer division in C++. When an integer is divided by another integer, the result is always an integer, and any remainder is discarded; this is what we call 'truncation'.

In the exercise, when we perform result = y / z, the division of 7 by 2 would normally result in 3.5. But since result is an integer variable, it can only store whole numbers. Thus, the .5 part is truncated, and result stores only the integer portion: 3.

Understanding truncation helps avoid logical errors in your program. For example, if accurate fractional values are critical for your calculation, using integer division would give you incorrect results. In such cases, you would need to use floating-point variables like float or double which can handle decimal values.