What Is Data Type Double?


Angela Bailey

In programming, the data type double is a fundamental concept that is used to represent floating-point numbers with double precision. It is an essential data type in various programming languages, including C++, Java, and Python. Double precision means that it can store a larger range of values and provide a higher level of precision compared to other numeric data types.

What Is a Floating-Point Number?

A floating-point number, also known as a real number, is a numerical value that can have both an integer and fractional part. It is commonly used for representing decimal numbers in computer programming. Floating-point numbers are essential for performing mathematical calculations involving non-integer values.

The Need for Double Precision

The double data type provides double precision compared to its counterpart, the float data type. While the float data type can store floating-point numbers with single precision (32 bits), the double data type uses twice as much memory (64 bits) to store floating-point numbers with higher precision.

The need for double precision arises when dealing with calculations that require accuracy over a wide range of values or when working with extremely small or large numbers. It eliminates or minimizes the rounding errors that may occur during mathematical operations.

Declaration and Usage

To declare a variable of type double in most programming languages, you would use the following syntax:

  • double variableName;

You can assign values to a double variable using numeric literals or by performing calculations:

  • double pi = 3.14159;
  • double result = 10.5 * 2.0;

Operations and Functions

The double data type supports various arithmetic and mathematical operations, including addition, subtraction, multiplication, division, and modulus. These operations can be performed using standard operators like +, -, *, /, and %.

In addition to basic operations, programming languages provide built-in functions for performing advanced mathematical computations using double precision. These functions include trigonometric functions (sin, cos, tan), exponential functions (exp, pow), logarithmic functions (log), and more.

Precision and Limitations

Despite its higher precision compared to the float data type, the double data type is not entirely immune to precision limitations. It can still encounter rounding errors when dealing with extremely large or small numbers or when performing complex calculations repeatedly.

It’s important to be aware of these limitations when working with double precision numbers to ensure accurate results. Some programming languages provide alternative libraries or data types for handling arbitrary precision arithmetic in situations where higher precision is required.


The double data type is a fundamental concept in programming used to represent floating-point numbers with double precision. It provides a larger range of values and higher level of precision compared to the float data type. Double precision is crucial for accurate mathematical calculations involving non-integer values over a wide range.

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