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Python If-else statements
Decision making is the most important aspect of almost all the programming languages. As the name implies, decision making allows us to run a particular block of code for a particular decision. Here, the decisions are made on the validity of the particular conditions. Condition checking is the backbone of decision making. In python, decision making is performed by the following statements. Statement Description If Statement The if statement is used to test a specific condition. If the condition is true, a block of code (if-block) will be executed. If - else Statement The if-else statement is similar to if statement except the fact that, it also provides the block of the code for the false case of the condition to be checked. If the condition provided in the if statement is false, then the else statement will be executed. Nested if Statement Nested if statements enable us to use if? else statement inside an outer if statement.
Indentation in Python
For the ease of programming and to achieve simplicity, python doesn't allow the use of parentheses for the block level code. In Python, indentation is used to declare a block. If two statements are at the same indentation level, then they are the part of the same block. Generally, four spaces are given to indent the statements which are a typical amount of indentation in python.
The if statement
The if statement is used to test a particular condition and if the condition is true, it executes a block of code known as if- block. The condition of if statement can be any valid logical expression which can be either evaluated to true or false. Figure - If else condition Flowchart: The syntax of the if-statement is given bel
if expression: statement
Example 1
num = int(input("enter the number?")) if num%2 == 0: print ("Number is even") Output: enter the number? Number is even
The if-else statement
The if-else statement provides an else block combined with the if statement which is executed in the false case of the condition. If the condition is true, then the if-block is executed. Otherwise, the else-block is executed. The syntax of the if-else statement is given below. if condition: #block of statements else : #another block of statements (else-block)
The break Statement
With the break statement we can stop the loop before it has looped through all the items:
Example
Exit the loop when x is "banana": city = ["Delhi", "Mumbai", "Agra"] for x in city: print(x) if x== "Mumbai": break
The continue Statement
With the continue statement we can stop the current iteration of the loop, and continue with the next:
Example
Do not print banana: city = ["Delhi", "Mumbai", "Agra"] for x in city: if x == "Mumbai": continue print(x)
The range() Function
To loop through a set of code a specified number of times, we can use the range() function, The range() function returns a sequence of numbers, starting from 0 by default, and increments by 1 (by default), and ends at a specified number.
Example
Using the range() function: for x in range( 6 ): print(x)
Else in For Loop
The else keyword in a for loop specifies a block of code to be executed when the loop is finished:
Example
Print all numbers from 0 to 5, and print a message when the loop has ended: for x in range( 6 ): print(x) else: print("Finally finished!")
Python While Loops
In coding, loops are designed to execute a specified code block repeatedly.
Introduction of Python While Loop
The Python while loop iteration of a code block is executed as long as the given condition, i.e., conditional_expression, is true. If we don't know how many times we'll execute the iteration ahead of time, we can write an indefinite loop.
- while conditional_expression:
- Code block of while The given condition, i.e., conditional_expression, is evaluated initially in the Python while loop. Then, if the conditional expression gives a boolean value True, the while loop statements are executed. The conditional expression is verified again when the complete code block is executed. This procedure repeatedly occurs until the conditional expression returns the boolean value False.
o The statements of the Python while loop are dictated by indentation.
o The code block begins when a statement is indented & ends with the very first unindented statement.
o Any non-zero number in Python is interpreted as boolean True. False is interpreted as None and 0.
Python While Loop Example
i= while i<=5: print(i * ‘*’) i=i+
