What Data Type Has Decimals?


Angela Bailey

When working with data in programming, it is essential to understand the different data types available. One common data type that often confuses beginners is the one that allows decimal numbers. In this article, we will explore the data type that handles decimals and how it can be used in various scenarios.

Decimal Data Type

The data type that supports decimal numbers is called float. The float data type represents a single-precision 32-bit floating-point number in most programming languages. It can store decimal values with a precision of approximately 7 digits.

In addition to float, some programming languages provide a double data type, which represents double-precision 64-bit floating-point numbers. This allows for higher precision and can store values with approximately 15 digits after the decimal point.

Why Use Decimal Data Type?

The need for a decimal data type arises when working with values that require high precision, such as financial calculations or scientific measurements. While integers can handle whole numbers efficiently, they cannot accurately represent fractional or decimal values.

For example, if you need to calculate the interest on a loan or perform complex mathematical operations involving fractions, using a decimal data type ensures accurate results without losing precision.

Using Float and Double

To use the float or double data types in your code, you must declare variables of these types. Here’s an example in C++:

#include <iostream>

int main() {
    float pi = 3.14;
    double gravity = 9.81;

    std::cout << "Value of pi: " << pi << std::endl;
    std::cout << "Value of gravity: " << gravity << std::endl;

    return 0;

In the above code snippet, we declare a float variable pi to store the value of pi (approximately 3.14). Similarly, we declare a double variable gravity to store the acceleration due to gravity (approximately 9.81 m/s²).

Caution: Floating-Point Precision

While using floating-point numbers, it is important to be aware of their limitations. Due to the way floating-point numbers are stored and represented in memory, they may not always provide exact precision.

This can lead to unexpected results during calculations. For example, adding or subtracting two floating-point numbers may produce a result with slight precision errors.

Rounding Errors

Rounding errors occur when the decimal representation of a number cannot be accurately stored in binary format. These errors accumulate with repeated calculations and can significantly affect the final result.

This issue becomes more noticeable when comparing two floating-point numbers for equality. Instead of using direct equality checks (a == b), it is recommended to use an epsilon value that defines an acceptable margin for comparison:

const double EPSILON = 0.00001;

if (fabs(a - b) < EPSILON) {
    // Numbers are considered equal


The float and double data types are crucial for handling decimal values in programming languages. They allow us to perform accurate calculations involving fractions and real numbers. However, it is essential to be cautious of floating-point precision limitations and rounding errors that can occur during calculations.

In summary, understanding how to use the float and double data types will enable you to work with decimal numbers effectively and produce accurate results in your programs.

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