IF, ELSE or ELIF (known as else if in some programming) are conditional statements which are used for execution of different code depends on condition. The if statements can be written without else or elif statements, But else and elif can’t be used without else. In this tutorial, you will learn if, else and elif in Python programming language.
1. Python if Statement
The single if statement is used to execute the specific block of code if the condition evaluates to true. In the case of false output, nothing will execute.
Syntax:
1 2 | if ( condition ): statements |
Example 1:
1 2 3 4 5 | #!/usr/bin/python var = 101 if ( var ): print "true" |
Example 2:
1 2 3 4 5 | #!/usr/bin/python var = 101 if ( var==101 ): print "true" |
2. Python if-else Statement
The if and else statement is used to execute the specific block of code for true condition and another block of code on false condition.
Syntax:
1 2 3 4 | if ( condition ): statements else: statements |
Example: Assinged a value to var variable, Now test if the assigned value it greated than 100. As per below code the result will be “Assigned value is greater than 100”.
1 2 3 4 5 6 7 8 | #!/usr/bin/python var = 101 if ( var > 100 ): print "Assigned value is greater than 100" else: print "Assigned value is less than or equals to 100" |
3. Python if-elif Statement
The if and elif (known as else-if) statement is used to execute the specific block of codes with multiple conditions. In this, if the main if the condition goes false then another elif condition is checked. You can define a number of elif conditions as per your requirements.
Syntax:
1 2 3 4 5 6 | if ( condition ): statements elif ( condition ): statements else: statements |
Example: Taken a avalue as input in total variable. Now compare the value with multiple levels and print the appropriate output.
1 2 3 4 5 6 7 8 9 10 11 12 | #!/usr/bin/python total = 90 if ( total > 500 ): print "total is greater than 500" elif ( total > 100 ): print "total is greater than 100" elif ( total > 50 ): print "total is greater than 50" else: print "total is less than or equal to 50" |
4. Python Nested if Statement
The nested if statements is use as if inside if. In this if any if condition evalutes to true then it goes to inner if condition.
Syntax:
1 2 3 4 5 | if ( condition ): if ( condition ): statements else: statements |
Example: taken 3 numeric inputs and find the greatest value. Like if var1 is greater than var2 then it check if var1 is also greater than var3.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | #!/usr/bin/python var1 = 100 var2 = 350 var3 = 80 if ( var1 > var2 ): if ( var1 > var3 ): print "var1 is greatest" else print "var3 is greatest" elif ( var2 > var3 ): print "var2 is greatest" else: print "var3 is greatest" |
Thanks mate! Straight forward and useful.