Understanding C++ function return values: an in-depth analysis of types and meanings

C Function return value type defines the data type returned by the function and its behavior: Basic type: Returns original data, such as integer, floating point number or Boolean value. Pointer type: Returns a reference to the memory address. Reference type: directly refers to the variable itself. void type: Indicates that the function does not return any value.

Understanding C function return values: Detailed explanation of types and meanings

Introduction
Programming in C , the return type of a function not only defines the type of data the function will return, but also provides important information about the behavior of the function itself. This article explores the types and meanings of C function return values ​​to help you understand their nuances.

Basic types
The most common return value types are basic types, such as int, float and bool. These types are used to represent the raw data returned by functions. For example:

int myFunction() {
  return 42;
}

This function returns a value of type int, representing the integer 42.

Pointer type
Pointer type is used to return a reference to a memory address. For example:

int* myFunction() {
  int* ptr = new int(10);
  return ptr;
}

This function returns a pointer to the memory address where the integer 10 is stored.

Reference types
Reference types are similar to pointers, but they refer directly to the variable itself instead of referencing the variable's address. For example:

int& myFunction() {
  int value = 10;
  return value;
}

This function returns a reference to the integer variable value, allowing the caller to directly modify the variable's value.

void type
void type means that the function does not return any value. For example:

void myFunction() {
  // ... 执行某些操作，但不返回任何值
}

This function does not return any value, but just performs some operation (such as printing a message or updating an internal variable).

Practical Case

The following is a practical case showing the role of the C function return value type:

class MyClass {
public:
  int getValue() { return 10; } // 返回基本类型值
  int* getPointer() { return &value; } // 返回指针值
  int& getReference() { return value; } // 返回引用值
  void doSomething() {} // 不返回任何值

private:
  int value = 42;
};

int main() {
  MyClass myClass;
  int myValue = myClass.getValue(); // 获取基本类型值（10）
  int* myPointer = myClass.getPointer(); // 获取指针值（引用内部值 42）
  int& myReference = myClass.getReference(); // 获取引用值（直接引用内部值 42）
  myClass.doSomething(); // 执行操作，不返回任何值
}

In this example:

• getValue() The function returns a basic type value 10.
• getPointer() The function returns a pointer to an internal variable value that stores the integer 42.
• getReference() The function returns a reference to the variable value, allowing the variable's value to be modified.
• doSomething() The function does not return any value, but just performs some operation.

By understanding these return value types, you can effectively write C functions so that they behave as expected.

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