The difference between passing values ​​and passing references in C++ function parameters

C There are two ways to pass function parameters: value transfer and reference transfer: Value transfer: Create a copy of the local variable, and modifications to the copy will not affect the original variable. Pass by reference: Directly pass the reference to the original variable, and modifications to the reference variable are reflected in the original variable.

C The difference between passing values ​​and passing references for function parameters

Passing values

When a function parameter is passed by value, a copy of the local variable is created. Changes to this copy do not affect the original variable.

Syntax:

void function(int value);

Pass reference

When function parameters are passed by reference, pass the reference to the original variable directly. , instead of creating a copy. Changes to the reference variable will be reflected in the original variable.

Syntax:

void function(int& value);

Practical case

Consider the following function:

void swap(int& a, int& b) {
  int temp = a;
  a = b;
  b = temp;
}

This function is passed by reference Two integers are passed, so when the function swaps the values ​​of a and b, it also modifies the original variable in the main function.

Usage example:

int main() {
  int x = 5, y = 10;
  swap(x, y); // 交换 x 和 y 的值
  cout << x << ", " << y << endl; // 输出交换后的值
  return 0;
}

Output:

10, 5

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