C++ function return values: an in-depth guide to types and meanings

C function return value specifies the data type returned by the function, which can be a built-in or user-defined type. The void type means no return value. The returned value can be used for further operations, such as printing the value returned by the function.

C Function Return Values: An In-Depth Guide to Types and Meanings

Understanding C Function Return Values

Functions in C play a vital role, they allow us to organize our code and perform specific tasks. Functions can return a value, which allows us to perform further operations on the result after calling the function. Understanding the types and meanings of function return values ​​is critical to using C effectively.

Return value type: Basics

The return value type of a C function specifies what type of value the function will return. The return value type can be a built-in type (such as int, float, bool) or a user-defined type (such as class, structure).

Return value type: Syntax

In C, we use the following syntax to declare the return value type of a function:

returnType functionName(parameters) {
  // 函数体
  return value;
}

For example:

int sum(int a, int b) {
  return a + b;
}

In this example, the sum() function returns an integer.

void: No return value

There is a special return value type in C called void. It means that the function will not return any value.

void printHello() {
  std::cout << "Hello, world!" << std::endl;
}

Practical case: Calculating the area of ​​a circle

Consider a function that calculates the area of ​​a circle:

double calculateArea(double radius) {
  const double pi = 3.14;
  return pi * radius * radius;
}

This function uses a double-precision floating point number as Parameters and returns a double precision floating point number as the area of ​​the circle.

Using function return values

The function return value can be used to perform further operations after the function call. For example, we can use the calculateArea() function to print the area of ​​a circle:

double radius = 5.0;
double area = calculateArea(radius);
std::cout << "Area of the circle: " << area << std::endl;

Conclusion

Understand the types and meanings of C function return values Essential for writing efficient and clear code. By following the principles outlined in this article, you can use functions with confidence and manage their return values ​​effectively.

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