# argument & parameter

Arguments and parameters are two terms that are often used interchangeably, but they have different meanings in programming. Here are the differences between argument and parameter:

* Parameter: A parameter is a variable in a function definition that acts as a placeholder for a value that will be passed to the function when it is called. It is a part of the function's signature and defines the type and number of values that the function expects to receive.
* Argument: An argument is a value that is passed to a function when it is called. It is the actual value that is assigned to the parameter of the function. Arguments are passed to a function in the order that the parameters are defined.

In summary, a **parameter** is a variable that is **defined in a function**, while an <mark style="color:red;">**argument**</mark> is the value that is <mark style="color:red;">**passed to that parameter when the function is called**</mark>.

## def gpa(self,student\_id:str) -> float:

The function definition "def gpa(self, student\_id:str) -> float" means that it is a Python function that takes in <mark style="color:green;">**two arguments**</mark>: "self" and "student\_id", where "<mark style="color:red;">**self**</mark>" refers to <mark style="color:red;">the instance of the class</mark> and "student\_id" is a string argument. The "-> float" part of the definition specifies that the function returns <mark style="color:green;">**a floating-point number (a decimal number)**</mark>. In other words, the function calculates and *<mark style="color:red;">returns</mark>* the GPA (grade point average) of the student with the given ID.&#x20;

## What is the purpose of the "self" parameter in Python class methods

In Python, the "self" parameter is used in class methods to refer to the instance of the class[1](https://www.programiz.com/article/python-self-why)[2](https://www.geeksforgeeks.org/self-in-python-class/)[3](https://www.edureka.co/blog/self-in-python/)[4](https://www.w3schools.com/python/gloss_python_self.asp). It is always the first parameter in a method definition and is passed implicitly when the method is called on an instance of the class[1](https://www.programiz.com/article/python-self-why)[2](https://www.geeksforgeeks.org/self-in-python-class/)[3](https://www.edureka.co/blog/self-in-python/). The "self" parameter **allows access to the attributes and methods of the class within the method**[1](https://www.programiz.com/article/python-self-why)[2](https://www.geeksforgeeks.org/self-in-python-class/)[3](https://www.edureka.co/blog/self-in-python/). It is used to **differentiate between instance variables and local variables within the method**[5](https://www.knowledgehut.com/blog/programming/self-variabe-python-examples). The use of "self" makes the code more readable and explicit, as it clearly indicates that the method is being called on an instance of the class

## "def display\_results(self) -> None:" and "def display\_results(self):"

the former specifies <mark style="color:purple;">**the return type**</mark> of the function, while the latter does not. **The "-> None"** in the first example indicates that the function <mark style="color:green;">**does not return anything.**</mark>

## Difference between "list" and "dictionary"

A <mark style="color:red;">**list\[]**</mark> is an ***ordered*** collection of elements, and each element can be accessed using its index. A <mark style="color:red;">**dictionary{}**</mark>, on the other hand, is an ***unordered*** collection of key-value pairs, and each value can be accessed using its key.

## print(title\[:-1]).     \[-1] in python

In Python, "print(title\[:-1])" means to print the "title" string without its last character.&#x20;

The **square brackets\[]** are used to <mark style="color:blue;">slice the string,</mark> and the <mark style="color:red;">**colon:**</mark> inside the brackets indicates that we want to slice the string. The ":-1" part of the code specifies the range of the slice, where the first colon indicates the start of the slice, and the "-1" indicates the end of the slice. In Python, <mark style="color:green;">**negative indices**</mark> are used to <mark style="color:orange;">count from the end of the string,</mark> so "-1" refers to the last character of the string. Therefore, ***"title\[:-1]" returns a new string that contains all the characters of the "title" string except for the last one.*** Finally, the "print()" function is used to display the resulting string on the console.

## print(k,end="") and print(k,end="{:>12}".format(""))

By default, the "end" parameter is set to <mark style="color:purple;">**"\n"**</mark>, which means that <mark style="color:purple;">a newline</mark> character is printed at the end of the output. However, by setting the <mark style="color:purple;">"end" parameter to an empty string</mark>, we can print the output <mark style="color:purple;">without a newline</mark> character.

The "{:>12}" part of the code is a <mark style="color:purple;">string formatting</mark> expression that specifies how the spaces should be formatted. The <mark style="color:purple;">">" character</mark> indicates that the spaces should be <mark style="color:purple;">right-aligned</mark>, while the "12" indicates the width of the field, which is 12 characters. Finally, the empty string <mark style="color:purple;">""</mark> is used to <mark style="color:purple;">fill the field with spaces</mark>.