C++ function call overloading mechanism: parameter passing and return value ambiguity processing

C Function overloading allows the definition of multiple variants of the same function name, distinguished by different formal parameter lists. There are two types of parameter passing: value passing and reference passing. Value passing copies the value to a local variable, and reference passing passes the reference to the function. Modifying the reference will affect external variables. Functions can return different types of values, including primitive data types, references, and objects.

C Function call overloading mechanism: Parameter passing and return value ambiguity handling

Introduction

C Function overloading allows multiple functions to be defined with the same function name, as long as their formal parameter lists are different. Through overloading, multiple variants of the same functional function can be implemented to facilitate parameter passing and ambiguity processing of return values.

Parameter passing

In function calls, there are two main ways to pass parameters:

• Value passing ( Pass-by-value): Copy the value of the parameter to the local variable inside the function. Modifications to local variables do not affect external variables.
• Pass-by-reference: Pass the reference of the parameter to the function. Modifications to reference variables affect external variables.

Return value

Another important aspect of function calls is the return value. Functions can return various types of values, including primitive data types, references, pointers, and objects.

Practical Case

The following is a practical case of C function overloading, demonstrating how to use different parameter passing methods and return value types in function calls:

#include <iostream>

using namespace std;

// 实现计算一个数的平方
int square(int num) {
  return num * num;
}

// 实现计算两个数的和并返回结果的引用
int& add(int& num1, int& num2) {
  num1 += num2;
  return num1;
}

int main() {
  int x = 5, y = 3;

  // 使用值传递调用 square() 函数
  int result1 = square(x);
  cout << "x 的平方是：" << result1 << endl;

  // 使用引用传递调用 add() 函数
  int& sum = add(x, y);
  cout << "x 和 y 的和是：" << sum << endl;

  return 0;
}

In this case, the square() function uses value passing to copy the value of x to the local variable num inside the function. Therefore, the square() function's modification of num will not affect the value of x.

On the other hand, the add() function uses pass-by-reference, passing references to x and y to the function. Therefore, modifications to reference variables by the add() function will affect the values ​​of x and y.

Conclusion

Function overloading is a powerful mechanism to achieve the same functionality in different situations. C allows developers to create flexible and reusable code through parameter passing and return value ambiguity.

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