Describe the behaviours that are governed by the rules that apply to functions that have default parameters.
Describe the behaviours that are governed by the rules that apply to functions that have default parameters.
Database System Concepts
7th Edition
ISBN:9780078022159
Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Chapter1: Introduction
Section: Chapter Questions
Problem 1PE
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![**Understanding Default Parameters in Functions**
**Describe the behaviours that are governed by the rules that apply to functions that have default parameters.**
In programming, when defining functions, default parameters can be set which allows the function to be called with fewer arguments than it is defined with. This provides flexibility in function calls and helps to simplify code. Here are some key behaviours governed by rules that apply to functions with default parameters:
1. **Setting Default Values:** When defining a function, you can assign default values to one or more parameters. If the function is called without specifying these parameters, the default values are used.
```python
def greet(name="Guest"):
print(f"Hello, {name}!")
```
In this example, calling `greet()` will print "Hello, Guest!" because the `name` parameter has a default value of "Guest".
2. **Order of Parameters:** If a function has both required and default parameters, the required parameters should come first in the function definition, followed by the parameters with default values.
```python
def display_student_info(name, age, grade="Not Assigned"):
print(f"Name: {name}, Age: {age}, Grade: {grade}")
```
Here, `name` and `age` are required parameters, and `grade` has a default value. Calling `display_student_info("Alice", 14)` will output "Name: Alice, Age: 14, Grade: Not Assigned".
3. **Overriding Default Values:** When a function is called with all parameters provided, the default values get overridden by the provided arguments.
```python
greet("Alice")
```
This will output "Hello, Alice!" instead of using the default "Guest".
4. **Evaluation of Default Values:** Default values are evaluated only once when the function is defined, not each time the function is called. This is especially important when using mutable default values like lists or dictionaries.
```python
def add_student(student, students_list=[]):
students_list.append(student)
return students_list
```
Calling `add_student('Alice')` followed by `add_student('Bob')` will result in both 'Alice' and 'Bob' being in the same list, since the list is shared across subsequent calls.
By understanding these behaviours, programmers can effectively utilize default parameters to write more concise and flexible functions.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fe910b5e3-40fa-4c71-820e-d8c04cc234bb%2F407f55e1-3f3c-49b5-973f-5e9bfdae800e%2Flv9var_processed.jpeg&w=3840&q=75)
Transcribed Image Text:**Understanding Default Parameters in Functions**
**Describe the behaviours that are governed by the rules that apply to functions that have default parameters.**
In programming, when defining functions, default parameters can be set which allows the function to be called with fewer arguments than it is defined with. This provides flexibility in function calls and helps to simplify code. Here are some key behaviours governed by rules that apply to functions with default parameters:
1. **Setting Default Values:** When defining a function, you can assign default values to one or more parameters. If the function is called without specifying these parameters, the default values are used.
```python
def greet(name="Guest"):
print(f"Hello, {name}!")
```
In this example, calling `greet()` will print "Hello, Guest!" because the `name` parameter has a default value of "Guest".
2. **Order of Parameters:** If a function has both required and default parameters, the required parameters should come first in the function definition, followed by the parameters with default values.
```python
def display_student_info(name, age, grade="Not Assigned"):
print(f"Name: {name}, Age: {age}, Grade: {grade}")
```
Here, `name` and `age` are required parameters, and `grade` has a default value. Calling `display_student_info("Alice", 14)` will output "Name: Alice, Age: 14, Grade: Not Assigned".
3. **Overriding Default Values:** When a function is called with all parameters provided, the default values get overridden by the provided arguments.
```python
greet("Alice")
```
This will output "Hello, Alice!" instead of using the default "Guest".
4. **Evaluation of Default Values:** Default values are evaluated only once when the function is defined, not each time the function is called. This is especially important when using mutable default values like lists or dictionaries.
```python
def add_student(student, students_list=[]):
students_list.append(student)
return students_list
```
Calling `add_student('Alice')` followed by `add_student('Bob')` will result in both 'Alice' and 'Bob' being in the same list, since the list is shared across subsequent calls.
By understanding these behaviours, programmers can effectively utilize default parameters to write more concise and flexible functions.
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