How to call functions in c++

Function calling in C involves the following steps: Define the function. Declare the function where it will be used. Call a function using its name and its arguments. Select the parameter passing method (pass by value or pass by reference) as needed.

How to call functions in C

Function calling in C is a key concept that allows blocks of code Repeat. To call a function, you need to follow the following steps:

1. Define the function

First, you need to define the function to be called. A function definition includes the function name, parameter list (if applicable), and function body.

2. Function declaration

Before calling a function, you need to declare the function at the location where the function is used. This tells the compiler that the function exists and allows it to parse the function call correctly.

3. Calling a function

To call a function, you need to use the function name and its parameters (if the function accepts parameters). Parameters are enclosed in parentheses and separated by commas.

4. Function call example

The following is a function call example:

<code class="cpp">#include <iostream>

using namespace std;

// 定义函数
void printMessage() {
  cout << "Hello, world!" << endl;
}

int main() {
  // 声明函数
  extern void printMessage();

  // 调用函数
  printMessage();

  return 0;
}</code>

When the above code runs, it will print "Hello, world !" to the console.

Function call parameter passing

Function calls can pass parameters by passing the parameter list to the function parameters. Parameter passing can be by value or by reference.

Value passing: In this passing method, the value of the parameter is copied to the parameter of the function. If you modify the parameter value in a function, it will not affect the parameter value of the calling function.

Pass by reference: In this passing method, the reference of the parameter is passed to the parameter of the function. If the value of a parameter is modified in a function, the parameter value of the calling function will be modified directly.

Select the parameter transfer method

As needed, you can choose the parameter transfer method according to the following guidelines:

• If you do not want to modify the parameter in the calling function Parameter values ​​are passed by value.
• If you need to directly modify the parameter value in the calling function, use reference passing.

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