Return value of C++ function: full analysis of type and meaning

C The return value type of a function defines the result of the function call, which can be a basic type (such as int) or a user-defined type (such as a class). The meaning of the return value depends on the purpose of the function and can represent success/failure, operation results, or other information.

The return value of C function: full analysis of type and meaning

In C, the return value of a function is passed in the function It is defined by specifying a type in the signature. The type of a function's return value can be a primitive type, such as int, float, or char, or a user-defined type, such as a class or structure.

Type of return value

The following are some common return value types:

• void: Represents a function There is no return value.
• int: Usually used to represent the result of a function, usually 0 (success) or non-zero (error).
• bool: Indicates the true or false value of the function, usually true or false.
• double: represents a floating point value.
• string: Represents a string.

The meaning of the return value

The meaning of the function return value depends on the specific purpose of the function. It can represent the success or failure of a function, the result of an operation performed, or any other information.

Practical case

The following is a function that calculates the area of ​​a circle:

double calculateArea(double radius) {
  return M_PI * radius * radius;
}

The return value type of this function is double, represents the area of ​​the circle.

In the main program, we can use this function like this:

#include <iostream>
using namespace std;

int main() {
  double radius;
  cout << "Enter the radius of the circle: ";
  cin >> radius;
  double area = calculateArea(radius);
  cout << "The area of the circle is: " << area << endl;
  return 0;
}

In this example, the return value of the calculateArea() function is stored in the area variable, and then output to the screen.

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