What are Functions?

Functions are fundamental building blocks in programming. They are reusable blocks of code designed to perform a specific task. Functions help make code more organized, readable, and easier to maintain. By using functions, you can break a large, complex program into smaller, manageable subroutines.

main


              1234
            
int main() // `main` is the name of a function
{
	return 0;
}

Note

The name main is already reserved by the C++ language. Therefore, when declaring a function with this name, the compiler will generate an error.

Creating a function involves several key steps to ensure it performs a specific task and integrates seamlessly into your program. A function consists of a return type, a name, parameters (if needed), and a body where the logic resides.


Define the type	Specify the type of data the function will return (e.g., `int`, `void`, etc.).
Assign a name	Give the function a meaningful name to identify it.
Provide a body	Write a block of instructions within curly braces `{...}` to define its functionality.

get_bank_name


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// Function to return the name of the bank
std::string get_bank_name() // type and name of function
{ 
    // Beginning of the function body
    std::string bank_name = "Future Savings Bank";
    return bank_name; // Return the name of the bank
    // End of the function body
}

After creating a function, the next step is to call it. Calling a function executes the code inside it and allows you to use its result (if it returns a value).

main


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#include <iostream>
#include <string>

// Function to return the name of the bank
std::string get_bank_name()
{ 
    std::string bank_name = "Future Savings Bank";
    return bank_name; // Return the name of the bank
}

int main()
{
	std::cout << "Name of the bank: " << get_bank_name() << std::endl;
}

Converting currencies is a common real-life task, especially in global transactions or travel. By creating a function, we can simplify this process, making the conversion reusable and efficient.

main


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#include <iostream>

// Function to convert USD to Euros
double convert_usd_to_eur(double usd_amount)
{
    const double exchange_rate = 0.91;
    double euros = usd_amount * exchange_rate;
    return euros;
}

int main()
{
    double usd = 100.0; // Amount in USD
    std::cout << usd << " USD = " << convertUsdToEur(usd) << " EUR" << std::endl;
}

function


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int add_numbers(int a, int b); // 'a' and 'b' are parameters

add_numbers(5, 10); // 5 and 10 are arguments passed to the function

In programming, arguments are values or variables that you pass to a function when calling it. These values provide the input the function needs to perform its task. By passing arguments, you can make functions more dynamic and reusable.


Function Parameters	Placeholders defined in the function header that specify the type and name of the data the function expects.
Arguments	The actual values or variables passed to a function when calling it, which are assigned to the corresponding parameters.
Passing Values to Variables	During a function call, arguments are assigned to the parameters. Inside the function, these parameters behave like regular variables.

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Section 5. Chapter 1