- None
Python is an high-level and general-purpose programming language. Created by Guido van Rossum and first released in 1991.It is object oriented and is dynamically typed.Python is meant to be an easily readable language and it often uses English keywords.
- Don't worry about the all the technical terms as we dive deep into the language you will learn all the things.
- For the time being you just have to know that:
- Python is a programming language not a snake 🐍.
- It is the easiest language which anyone can learn in no time.
- And currently it is the most loved and most famous programming language of 2020.
- And we will be using Python3 over Python2.
So lets type our first line of code.This is the code which every person in the world types when they start to learn programming.
print("Hello, World!")
print("DevIncept")Here print is a function which is builtin, which takes anything written in the parenthesis and the quotes(''/"") and prints it out on the screen. You can try printing anything in the jupyter notebook provided.
Variables are the names you give to computer memory locations which are used to store values in a computer program OR Variables are containers for storing values.A variable is created the moment you first assign a value to it.
Name= 'John'
Age= 19
Company= 'DevIncept'
print(Name,Age,Company)Result:
John 19 DevInceptAs we can see in the above example Name, Age and Company are three different variables all having different values.And when the variable names are called in the print function they are printed on the screen.
A variable can store only one value, as we continue through the program from top to bottom, if the same variable name is assigned with different value the new value takes over the previous one,Variables do not need to be declared with any particular type and can even change type after they have been set..As in the below example:
x=19
x='DevIncept'
print(x)Result: DevIncept
x=19
x=23
print(x)Result: 23
Unlike other programming languages, Python has no command for declaring a variable.
As we now know what are variables and how are they used now lets see some very important rules to create a valid Variable Name. Note: Rules for Naming of Variables are same in almost all programming languages.
- A variable name must start with a letter or the underscore character
- A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )
- A variable name cannot start with a number
- Variable names are case-sensitive (age, Age and AGE are three different variables)
- There should be no spaces in the words
#Valid Variable names
myvariable1="DevIncept"
my_variable="JaneDoe"
_variable=17
#Invalid Variable names
invalid-variable='Mahendra'
8variable=19
invalid name='Doe'When you run the above lines of code when the Pyhton Interpreter reaches Invalid Variable names it raises an Syntax Error.Don't worry check your code correct it and carry on.
fruit,color,cost= "Apple","Green",15.75
print(fruit)
print(color)
print(cost)Result:Apple Green 15.75
So this here finishes the basics of Variables hope you enjoyed the topics.
Remeber all those variables which we created in the above lessons, we saw there were plain numbers, decimal numbers, and simple text. These are nothing but different Data Types. !!!Shocker huh 😆, all this time you were using data types and you didn't know what they were.😲
- In programming, data type is an important concept.
- Variables can store data of different types, and different types can do different things.
Some basic and most commonly used datatypes.
| Data Type | Abbreviation | Examples |
|---|---|---|
| str | text type | 'Ron', 'Remi' |
| int | integers | 10, 5 |
| float | decimal | 10.5, 5.7 |
| bool | True/False | True ,False |
For more advanced and all datatypes you check out the following site ---->> RealPython
Above mentioned Data types are most commonly used. And whenever you are not sure what datatype the object is you can use the type() function.
name="DevIncept"
print(type(name))Result: <class 'str'>
age=20
print(type(age))Result: <class 'int'>
- int: Int, or integer, is a whole number, positive or negative, without decimals, of unlimited length.
- float: Float, or "floating point number" is a number, positive or negative, containing one or more decimals.
#int
x=123
y=-987
z=687969176975
#float
a=23.897
b=-4.87970879879
print(type(x))
print(type(y))
print(type(z))
print(type(a))
print(type(b))Result:
<class 'int'>
<class 'int'>
<class 'int'>
<class 'float'>
<class 'float'>In real world what do we do with numbers???😏😏 Calculations right, in python also we can tell the program to do calculations.
a=30
b=20
sum=a+b #does the addition
diff=a-b #does the subtraction
div=a/b #does the division
print(sum)
print(diff)
print(div)Result:
50
10
1.5You can convert one type to another by using int(),float() methods.
a=5 #int
b=7.7 #float
#converting from int to float:
x=float(a)
#converting from float to int:
y=int(b)
print(x)
print(y)
print(type(x))
print(type(y))Result:
5.0
7
<class 'float'>
<class 'int'>Note: You can also specify the type in the starting only its called Python Casting
x=int("56") # x will be 56
y=int(8.9) # y will be 8
z=float(56) # z will be 56.0
a=str(56) # a will be '56'String literals in python are surrounded by either single quotation marks, or double quotation marks.
'hello' is the same as "hello".
print('hello')
print("hello")
#Strings assigned in variables
a= 'DevIncept'
print(a)
#Multiline Strings
a = """Lorem ipsum dolor sit amet,
consectetur adipiscing elit,
sed do eiusmod tempor incididunt
ut labore et dolore magna aliqua."""
print(a)Result:
hello
hello
DevIncept
Lorem ipsum dolor sit amet,
consectetur adipiscing elit,
sed do eiusmod tempor incididunt
ut labore et dolore magna aliqua.Strings are very important Data types, There are lots of things you can do with strings For example: Square brackets can be used to access elements of the string.
a='DevIncept'
print(a[0]) #prints the first letter
print(a[-1]) #prints the last letter
print(a[2]) #prints the third letterYou must be wondering i told it will print the first letter but wrote zero(0) in the square bracket.??:smile: Thats a totally valid question. All programing languages are mostly zero-indexed meaning the positioning of the first letter is the considered as zero(0) and not one(1) Result:
D
t
vConcatenation in general means to combine things. As the general meaning, in programming also it means the same you can combine strings using + operator
a="DevIncept "
b="is a great "
c="Company"
print(a+b+c)Result:
DevIncept is a great Company
You can return a range of characters by using the string slicing. Specify the start index and the end index(not included), separated by a colon, to return a part of the string.
a='DevIncept'
print(a[0:3])Result:
DevString Methods are nothing but pyhton built in fuctions to make our life easy...
a='DevIncept'
print(a.lower()) # all lowercase
print(a.upper()) # all uppercaseResult:
devincept
DEVINCEPT
You can find more String methods ------>> Python-Ds
To insert characters that are illegal in a string, use an escape character. An escape character is a backslash \ followed by the character you want to insert.
txt = "We are the so-called \"Vikings\" from the north."
print(txt)Result:
We are the so-called "Vikings" from the north.
Other Escape Characters used in python are:
| Code | Result |
|---|---|
| \' | Single Quote |
| \\ | Backslash |
| \n | New Line |
| \r | Carriage Return |
| \t | Tab |
In programming you often need to know if an expression is True or False. You can evaluate any expression in Python, and get one of two answers, True or False.
print(10 > 9)
print(10 == 10)
print(10 < 9)
a=100
b=200
print(a>b)Result:
True
True
False
False