How to call functions in c++

There are two ways of calling functions in C: value calling and reference calling. A value call passes a copy of the parameter and does not affect the original variable; a reference call passes a parameter reference, and modifying the reference will affect the original variable. Based on the function purpose and efficiency considerations, choose the appropriate calling method: value calling protects the original variable, and reference calling modifies the original variable.

How to call functions in C

In C, there are two main ways to call functions: value Calls and reference calls.

Value calls

Value calls pass a copy of the function parameters. When the function is executed, any modifications made to the copy of the parameters will not affect the original variables.

<code class="cpp">void increment(int x) {
  x++;  // 仅修改副本
}

int main() {
  int y = 5;
  increment(y);  // 不会修改 y 的值
  cout << y;  // 输出 5
  return 0;
}</code>

Reference call

Reference call passes the reference of the function parameter. When the function is executed, any modifications to the parameter references will affect the original variables.

<code class="cpp">void increment(int& x) {  // 接受引用作为参数
  x++;  // 修改原始变量
}

int main() {
  int y = 5;
  increment(y);  // 会修改 y 的值
  cout << y;  // 输出 6
  return 0;
}</code>

Select the calling method

Which calling method to choose depends on the purpose of the function and efficiency considerations:

• Value call:

  • Used when the original variable needs to be protected from modification by the function.
  • is more efficient for passing large structures or class types because unnecessary copies are avoided.

• Reference call:

  • Use when the function needs to modify the original variable.
  • is more efficient for passing basic types because unnecessary copies are avoided.

#Understanding these two calling methods is critical to using C functions efficiently and safely.

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