Subtraction Operator in C++

The subtraction operator (-) in C++ is used to subtract one value from another. It can be applied to a variety of data types, including integers, floating-point numbers, and characters. Understanding how subtraction works with different types of data is essential for performing calculations in any C++ program.

Syntax

result = operand1 - operand2;

• operand1 and operand2 can be constants, variables, or expressions.
• The result holds the difference between the two values.

1. Integer Subtraction

When subtracting two integers, the result is an integer.

int a = 15, b = 7;
int result = a - b;
std::cout << "Difference: " << result;  // Output: 8

2. Floating-Point Subtraction

When dealing with float or double, subtraction provides results with decimal precision.

float x = 10.5, y = 3.2;
float result = x - y;
std::cout << "Difference: " << result;  // Output: 7.3

double m = 100.55, n = 50.25;
double result = m - n;
std::cout << "Result: " << result;  // Output: 50.3

3. Integer and Floating-Point Mixed Subtraction

C++ automatically promotes the lower type (int) to the higher type (float/double) during mixed-type operations.

int a = 20;
double b = 4.75;
double result = a - b;
std::cout << "Result: " << result;  // Output: 15.25

4. Character Subtraction

Characters are internally stored as ASCII values. Subtracting characters gives the difference between their ASCII codes.

char a = 'D'; // ASCII 68
char b = 'A'; // ASCII 65
int result = a - b;
std::cout << "Result: " << result;  // Output: 3

5. Subtraction in Expressions

Subtraction is often used in mathematical expressions and formulas.

int result = (10 + 5) - (3 * 2);  // 15 - 6 = 9
std::cout << "Result: " << result;

Practice Examples

Example 1: Finding Age Difference

int age1 = 30, age2 = 24;
int diff = age1 - age2;
std::cout << "Age Difference: " << diff;

Example 2: Subtracting Float Measurements

float originalWeight = 65.75, lostWeight = 2.5;
float currentWeight = originalWeight - lostWeight;
std::cout << "Current Weight: " << currentWeight;

Example 3: Character Distance

char first = 'z', second = 'v';
int gap = first - second;
std::cout << "Gap between characters: " << gap;

Summary Table

Notes

• Subtraction is left-associative and follows standard arithmetic rules.
• When subtracting different types, the result type is automatically determined by promotion rules.
• Subtracting characters is a valid technique in ASCII-based calculations, such as alphabetical distance.