How to use double in c++

The double type in C is used to represent double-precision floating point numbers, with a storage size of 8 bytes, a value range of -1.7976931348623157e 308 to 1.7976931348623157e 308, and a precision of approximately 15-16 decimal digits. They can be used as variables, support arithmetic operations, and use floating-point format specifiers for input and output.

Using double in C

double type

double is a floating point type in C, used to represent hexadecimal floating point numbers. It is an implementation of the IEEE 754 double-precision floating point format.

Features

• Storage size: 8 bytes
• Value range: - 1.7976931348623157e 308 to 1.7976931348623157e 308
• Precision: Approximately 15-16 decimal digits

Syntax

The syntax for declaring a double variable is as follows:

double variable_name;

Assignment

can be double through literals, calculations or function calls. Variable assignment:

double num = 3.14;
double result = sqrt(16.0);

Operation

double Variables support basic arithmetic operations, including addition (), subtraction (-), Multiplication (*), division (/) and modulo (%).

Formatted input and output

You can use the std::cout and std::cin functions double For input and output of variables, you need to use the floating point format specifier %f:

std::cout << "Number: " << num << std::endl;
std::cin >> num;

Example

The following is a usagedouble Example of calculating pi type:

#include <iostream>

int main() {
  double radius = 5.0;  // 半径
  double circumference;  // 周长

  circumference = 2 * 3.14159265358979323846 * radius;

  std::cout << "圆周率为: " << circumference << std::endl;

  return 0;
}

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