Python syntax and fundamentals

Python Syntax:

Python syntax can be written directly in the Visual Studio Code. For example, a print statement or any line of code can be written directly in the program. In contrast, in other programming language such as Java/c++, print and other lines of code typically need to be enclosed within a main() function.

Python Indentation:

Python Indentation is crucial in the language, as it defines the structure of the code. It signifies the spaces at the begining of code lines.

if i<5:

print i //program will execute successfully

if the indentation is missed, then the program will throw a syntax error.

if i<5:

print i //will throw an error

Python Comment line:

Comments in Python are used to annotate code for readability and explanation. They are ignored by the Python interpreter during execution.

1. Single line Comment - starts with # symbol -any text following # on the same line is considered as a comment, and is ignored by the interperter.

   print("Hello World") #This will print the statement "Hello World"

2. Multiline comment - starts with triple quotes """ <code> """ - any text/line of code mentioned in the triple quotes """ """ is considered as the comment line, and this will be ignored by the interperter.

   """

   if i<5:

   print(i) //this entire if statement will be ignored if it's mentioned in the triple quotes.

   """

Python Variable:

Creating Variables:

A Python variable is created once you assign a value to it.

eg: i = 5 # i holds the integer value

j="Hello" #j holds the string value.

J="Hello" #uppercase J and lowercase j are different variable. J will not overwrite j

k=l="123" #k & l holds the string value.

a,b,c="Test","bat","cat" # a holds Test, b holds bat, c holds cat value

Rules for creating the variable:

1. Variable name starts with uppercase or lowercase letter.

2. Variable name cannot start with numbers but can contain numbers elsewhere.

3. Special characters are not allowed expect for the underscore(_), but it cannot be used at the beginning of the variable name.

4. Spaces are not allowed in variable names.

Casting:

Converting one datatype to another type.

i=5 #here i holds integer value

j=str(i) #here i value is converted to string

print(type(j)) #prints <class 'str'> indicating j now holds the string value

Type:

The type(), displays the datatype of a variable.

eg: i=5.5

print(type(i)) #displays <class 'float>, indicating i holds a float value

DataTypes:

Built-in data types:

1. Text type: str

2. Numeric type: int, float, complex

3. Sequence type: list, tuple, set

4. Mapping type: dictionary

5. Boolean type: bool

a="hello" # a holds string type

b=1 # b holds integer type

c=2.2 # c holds float type

li=[1,2,"helo", 3.4, 2+3j] #li holds list value

tu=(1,2,"helo", 3.4, 2+3j) #tu holds tuple value

se={1,2,"helo", 3.4, 2+3j} #se holds set value

di={a:1,b:2,c:"helo", d:3.4, e:2+3j} #di holds dictionary value with key-value pairs

boolean can hold True, False, 0, 1 value, True and 1 hold the same meaning, as do False and 0