C++ Output Numbers

Welcome to The Coding College! In this guide, we’ll explore how to print numbers in C++ using the std::cout object. Whether you’re displaying integers, floating-point numbers, or formatted data, this tutorial will help you get started.

Printing Numbers in C++

In C++, numbers can be printed directly using std::cout. This includes integers, floating-point numbers, and even calculations.

Example: Basic Output of Numbers

#include <iostream>  

int main() {  
    std::cout << 42 << std::endl;  // Prints an integer  
    std::cout << 3.14 << std::endl;  // Prints a floating-point number  
    return 0;  
}  

Output:

42  
3.14  

Printing Variables

You can also output numbers stored in variables.

Example: Using Variables

#include <iostream>  

int main() {  
    int age = 25;  
    float pi = 3.14159;  

    std::cout << "Age: " << age << std::endl;  
    std::cout << "Value of Pi: " << pi << std::endl;  

    return 0;  
}  

Output:

Age: 25  
Value of Pi: 3.14159  

Printing Mathematical Expressions

C++ allows you to directly output the results of mathematical operations.

Example: Printing Calculations

#include <iostream>  

int main() {  
    int a = 10, b = 5;  
    std::cout << "Addition: " << a + b << std::endl;  
    std::cout << "Multiplication: " << a * b << std::endl;  
    std::cout << "Division: " << a / b << std::endl;  
    return 0;  
}  

Output:

Addition: 15  
Multiplication: 50  
Division: 2  

Formatting Output

Sometimes, you may want to format the numbers for better readability.

1. Controlling Decimal Places

Use the <iomanip> library for precise formatting.

Example: Set Decimal Precision

#include <iostream>  
#include <iomanip>  

int main() {  
    double number = 3.1415926535;  

    std::cout << "Default: " << number << std::endl;  
    std::cout << "Fixed Precision (2): " << std::fixed << std::setprecision(2) << number << std::endl;  
    return 0;  
}  

Output:

Default: 3.14159  
Fixed Precision (2): 3.14  

2. Aligning Numbers

Use std::setw to set the width for alignment.

Example: Right-Aligned Output

#include <iostream>  
#include <iomanip>  

int main() {  
    int num1 = 123, num2 = 45;  

    std::cout << std::setw(5) << num1 << std::endl;  
    std::cout << std::setw(5) << num2 << std::endl;  
    return 0;  
}  

Output:

  123  
   45  

Working with Different Data Types

1. Integer Types

C++ supports various integer types (int, long, short, unsigned).

Example:

#include <iostream>  

int main() {  
    int num = 42;  
    unsigned int uNum = 100;  

    std::cout << "Integer: " << num << std::endl;  
    std::cout << "Unsigned Integer: " << uNum << std::endl;  

    return 0;  
}  

2. Floating-Point Types

C++ supports float, double, and long double for decimal numbers.

Example:

#include <iostream>  

int main() {  
    float fNum = 3.14;  
    double dNum = 3.14159;  

    std::cout << "Float: " << fNum << std::endl;  
    std::cout << "Double: " << dNum << std::endl;  

    return 0;  
}  

Tips for Printing Numbers

1. Use Proper Formatting: For financial or scientific calculations, format numbers using libraries like <iomanip>.
2. Label Outputs Clearly: Always provide context for the numbers being displayed.
3. Avoid Magic Numbers: Use variables to make your code more readable.

Learn More with The Coding College

Mastering output is a crucial part of programming. At The Coding College, we provide step-by-step tutorials to help you grasp the nuances of C++ output, formatting, and more.

What’s Next?

1. Practice printing numbers with different data types and formats.
2. Explore input handling using std::cin.