A function in Python is a block of code that performs a specific task and returns a result. Functions help break down a program into smaller, more manageable pieces and make the code easier to read, test, and maintain. Functions define using the defkeyword, followed by the name of the function, a set of parentheses, and a colon. The code within the function indent under the definition and execute when the function can call.
def func_name (optional_arguments)
statement
…
return optional_value
Arguments:Functions accept arguments, which values pass to the function when it calls and it specify in the parentheses of the function definition, however it use within the function to perform the desire task.
Return statement:Functions can return a result to the caller using the return statement for any data type, including numbers, strings, lists, dictionaries, etc. If a function doesn’t return a value, it returns None by default.
Scope:Variables can define inside a function are local to that function, it is not accessible outside of it. Variables define outside of a function can call global variables and can access from anywhere in the program.
Recursion:Functions can call themselves; this technique is recursion. Recursive functions are useful for solving problems that can break down into smaller, similar subproblems.
Default arguments:These arguments are used in the function definition but if a value doesn’t provide for a default argument, the default value will be used.
Keyword arguments: Functions can call using keyword arguments, which specify as key=value pairs but Keyword arguments allow you to specify arguments in any order if the names of the arguments can be provided.
Functions are a fundamental building block of Python programming and are essential for writing clean, reusable, and maintainable code.
Data structure in python makes it possible to store and organize data in a very efficient way. Using it, we can link the data together and perform the desired operations on them.
In programming, this process is especially important because it enables us to access and recall data more easily.
There is four general Data Structures in Python:
List: ordered, changeable, duplicate members.
Dictionary: ordered, changeable, No duplicate members.
Set: unordered, unchangeable, unindexed, No duplicate members.
Tuples: ordered, unchangeable, duplicate members.
LIST:
>>>a = []
for example:
>>>a = [2, 5, 10] >>>b = [1.2, 5.9, “Hi”, 8]
To recall form List: >>>a [0] result: 2 >>>a [1] result: 5
To change in List : >>>a [0]=3 >>>a result a[3, 5, 10]
With Python Standard Library, we call module code that is ready to use. We cannot use these modules without recall and if we need, we must call them.
The Python standard library is very extensive and offers many features. In this library, we see internal modules that are often written in C language. For example, we can access the file input/output system through these modules, without these modules, Python programming will be inaccessible.
These modules provide increased programming capabilities. In the installed version of Python in Windows or Mac, usually the entire standard library also install and accessible and there is no need to add them, but in Unix, they are a set of packages that we can install separately.
Modules are the main unit of code in Python and there are two types of modules in Python:
Pure module: This module is written in Python and is in a .py file
Extension module: This module is written in these languages: C/C++ for Python, Java for Python.
we have many Modules in Python, for example Modules:
OS: operating system dependent functionality
Random: random number generators
Datetime: manipulating dates and times
Sys: information about system
Collection: data structure and datatypes providing
How we can recall a library in Python:
for recalling, we have two options:
Recall all module: In this way, we recall all module and when we want to use commande we write module. Submodule (X)
Recall a specific sub module: In this way, in command we write just submodule (X), and it doesn’t need to write module name before submodule
WHILE loop is especially useful in Python programming, and we use it many times. In the WHILE loop, we start a loop until the condition in the loop becomes True and the loop stops.
In this loop, while first evaluates the desired condition, if the condition is correct, the command inside the loop is executed. After that, the condition is reevaluated and this process continues until the desired condition is violated and when the condition becomes False, the loop will stop.
Syntax:
while condition:
statement
In WHILEloop, we need a condition to stoploop, if we don’t write a condition to stop, loop will continue without stop. here are some examples:
while a > X:
print(‘Y’) →a=a-1
while a >= X:
print(a) →a-=1
Example :
a=1
while a <= 5:
print (a)
a=a+1
Output:
1
2
3
4
5
Example :
a=1
while True:
print (a)
if a==5:
break
a=a+1
Output :
The output for this example is same as the last one, I just wanted to teach you the same result in two ways.
Infinite while Loop in Python:
In this model of the loop, if the condition is True, the loop will run for infinity. In Python, to prevent this model of infinite loops, a workaround has been considered that if the compiler detects that the loop is not able to stop, it stops automatically. To avoid such infinite loops, we need a condition in the loop to stop.
Loops are used for sequential traversal, that’s mean used for repeating variables such as numbers, strings, lists or sets. The loop continues until it is terminated by the variable or by terminating the loop with the Break command. In this section, we want to learn how to use loops. loop in programming languages is an iterative method and is also found in other object-oriented languages. With a loop, we can execute a set of commands, once for each item. Loops in every programming language start with a set of rules, but they may be slightly different in structure. Python also has statements and conditional loops.
In the first part, we will introduce the FOR-loop Python. With this loop, we can iterate through instructions based on the number considered in the loop. First, we examine its structure:
for<var> in<iterable>:
<statement(s)>
In this structure, the “statement” repeats i times
let’s to see some example
for i in “Hello”:
print(i)
The output of this command: in five lines it prints Hello, line 1 first character, line 2 second character and …
for i in “Hello”:
print(1)
The output of this command: in five lines it prints 1, line 1 print 1, line 2 print 1 and …
for i in “55”:
print(i)
The output of this command: in two lines it prints 55, line 1 print 5, line 2 print 5 and …
if we want to print for example from 1 to 50, we can use command range(): in this command we can make [start,stop,step]
for i inrange (3):
print(i)
The output of this command: in three lines it prints: line 1 print 0, line 2 print 1 and line 3 print 2
We must know range (3), prints 0,1,2. If we want to print 1,2,3 = for i inrange (1,3+1)
With [step] we can skip numbers, for example: this prints 1,3,5 = for i inrange (1,5+1,2):
