How to use functions in c++

C function is an independent unit of code that performs a specific task and involves the following steps: declare the function, specifying the name, return type, and parameters; define the function, provide the function body and execution code; call the function, use its name and provide actual parameters.

Usage of functions in C

A function is an independent unit of code that performs a specific task. Using functions in C is very simple:

1. Declaring a function

The declaration of a function specifies the function's name, return type, and parameters. For example:

int sum(int a, int b);

2. Define the function

The definition of the function provides the implementation of the function. It includes the function body, which contains the code to be executed. For example:

int sum(int a, int b) {
  return a + b;
}

3. Calling a function

To call a function, just use its name and provide the actual parameters. For example:

int result = sum(10, 20);

Parameter passing

Function can pass parameters by value, reference or pointer.

• Value transfer: Operations on parameter copies will not affect the original variables.
• Passing by reference: Pass the reference of the parameter, and modifications to the reference will also affect the original variable.
• Pointer passing: Pass the pointer to the parameter. Modifying the value pointed to by the pointer will affect the original variable.

Return type

A function can return a value or no value. Functions that do not return a value are called void functions. The type of the return value is specified in the function declaration.

Example

Here is a simple example of using a function in C:

#include <iostream>

int main() {
  int a = 10;
  int b = 20;
  int result = sum(a, b);
  std::cout << "The sum is: " << result << std::endl;
  return 0;
}

int sum(int a, int b) {
  return a + b;
}

Output:

<code>The sum is: 30</code>

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