What Is Double Data Type With Example?


Larry Thompson

A common data type used in programming is the double data type. In this article, we will explore what the double data type is and provide examples to help you understand its usage.

What is a Double Data Type?

The double data type is a fundamental data type in programming that represents decimal numbers with a higher precision compared to the float data type. It is often used when more accuracy is required in calculations or when dealing with large numbers.

To declare a variable of the double data type, you can use the following syntax:

    double myDouble = 3.14159;

In this example, we declare a variable named myDouble and assign it the value of 3.14159. Note that we use the double keyword to indicate that it is of the double data type.

Why Use Double Instead of Float?

The float data type can also represent decimal numbers, so why use double instead? The main reason is precision. The double data type provides more precision compared to float, allowing for greater accuracy in calculations.

The float data type uses 32 bits to store a value, while the double data type uses 64 bits. This larger size allows doubles to store larger numbers and maintain a higher level of precision.

Example Usage:

To illustrate how the double data type can be used in practice, consider the following example:

    double radius = 5.0;
    double pi = 3.14159;
    double area = pi * radius * radius;

In this example, we calculate the area of a circle using the formula: area = π * r^2. We declare three double variables: radius, pi, and area.

We then calculate the area by multiplying the radius by itself and then multiplying it by π. The result is stored in the area variable.

The use of double allows us to have a more precise result for the area calculation compared to using float, which could introduce rounding errors.


The double data type provides higher precision for decimal numbers compared to float. It is commonly used when accuracy is essential or when dealing with large numbers. By using double, you can ensure your calculations are more precise and minimize rounding errors.

In this article, we explored what the double data type is and provided an example of its usage in calculating the area of a circle. Remember to take advantage of this data type when precision is crucial in your programming projects!

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