---
title: 6.8 Default Arguments
description: Default arguments allow a function parameter to have a predefined value that is used when the caller does not provide a corresponding argument. They make it possible to call the same function with different numbers of arguments while maintaining a…
url: "https://edcret.in/docs/cpp-programming/functions/6-8-default-arguments/"
updated: "2026-09-06"
category: C++ Programming / Functions
---

# 6.8 Default Arguments

Default arguments allow a function parameter to have a predefined value that is used when the caller does not provide a corresponding argument. They make it possible to call the same function with different numbers of arguments while maintaining a single function definition.

A default argument is specified in the function declaration or definition by assigning a value to the parameter. Once a default value is provided, subsequent parameters in the same parameter list must also have default values.

## Source Code

```
#include <iostream>

void greet(std::string name = "User")
{
    std::cout << "Hello, " << name << "!\n";
}

int main()
{
    greet();
    greet("Alice");

    return 0;
}
```

## Output

```
Hello, User!
Hello, Alice!
```

## Explanation

- `name = "User"` specifies `"User"` as the default argument for the `name` parameter.
- `greet()` is called without an argument, so the default value `"User"` is used.
- `greet("Alice")` provides an argument explicitly, so `"Alice"` replaces the default value.
- Default arguments are used only when the corresponding argument is omitted from the function call.
- Default arguments are specified using the assignment operator (`=`) in the parameter list.
- Once a parameter has a default argument, parameters appearing after it must also have default arguments.
- Default arguments can reduce the number of overloaded functions required for cases where parameters have common default values.
- `return 0;` terminates the program successfully.