User defined functions in C++
C++ User-defined functions
User-defined functions in C++ are functions that are created by the user to perform a specific task. These functions can be called from anywhere within the program, just like built-in functions. In C++, you can define your own functions to perform specific tasks.
Function definitions can be placed anywhere in a C++ program, but it is common to define all functions at the beginning of the program before the main function. This allows the program to use the functions before they are defined.
User defined functions in C++
In C++, a user-defined function is a block of code that performs a specific task and can be called multiple times in a program.
Syntax:
return_type function_name(parameter list) {
// function body
}
- The
return_typespecifies the data type of the value that the function returns. If the function does not return a value, thereturn_typeshould be void. - The
function_nameis the name by which the function can be called. - The
parameter listspecifies the input arguments that are passed to the function. - The
function bodycontains the code that is executed when the function is called.
User-defined functions Types
In C++, there are 4 different types of user-defined functions which are:
1) Function with no parameter and no return value
A user-defined function in C++ that has no parameters and no return value, also known as a void function, is a block of code that performs a specific task but does not take any input and does not return any output.
Example 1:
#include <iostream>
using namespace std;
void print_message() {
cout << "PrepInsta Prime" << endl;
}
int main() {
print_message(); // Calling the function
return 0;
}
Output:
PrepInsta Prime
2) Function with no parameter but return value
A user-defined function in C++ that has no parameters but has a return value, is a block of code that performs a specific task and returns a value of a specific data type but doesn’t take any input.
Example 2:
#include <iostream>
#include <cstdlib>
using namespace std;
int get_random_number() {
return rand() % 10 + 1;
}
int main() {
cout << "Random number: " << get_random_number() << endl;
return 0;
}
Output:
Random number: 4
3) Function with parameter but no return value
A user-defined function in C++ that has parameters and no return value, also known as a void function, is a block of code that performs a specific task and takes input in the form of function parameters, but does not return any output.
Example 3:
#include <iostream>
using namespace std;
void print_string(string input) {
cout << "Input: " << input << endl;
}
int main() {
string message = "PrepInsta Prime";
print_string(message); // Calling the function
return 0;
}
Output:
Input: PrepInsta Prime
4) Function with parameter and return value
A user-defined function in C++ that has parameters and a return value is a block of code that performs a specific task, takes input in the form of function parameters, and returns a value of a specific data type.
Example 4:
#include <iostream>
using namespace std;
int multiply(int x, int y) {
return x * y;
}
int main() {
int a = 2, b = 3;
int result = multiply(a, b);
cout << "Result: " << result << endl;
return 0;
}
Output:
Result: 6
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