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Python Conditional Statements: IF…Else, ELIF &, Switch Case, By Steve Campbell, , Updated January 6, 2022, , What are Conditional, Statements in Python?, Conditional Statement in Python perform, different computations or actions depending, on whether a specific Boolean constraint, evaluates to true or false. Conditional, statements are handled by IF statements in, Python., In this tutorial, we will see how to apply, conditional statements in Python., What is If Statement? How to Use it?, What happen when “if condition” does not meet, How to use “else condition”, When “else condition” does not work, How to use “elif” condition, How to execute conditional statement with minimal code, Python Nested if Statement, Switch Case Statement in Python, , What is Python If Statement?, Python if Statement is used for decision-making operations. It contains a body of code which, runs only when the condition given in the if statement is true. If the condition is false, then, the optional else statement runs which contains some code for the else condition., When you want to justify one condition while the other condition is not true, then you use, Python if else statement.

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Python if Statement Syntax:, , if expression, Statement, else, Statement, , Python if…else Flowchart, , Let’s see an example of Python if else Statement:

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This code is editable. Click Run to Execute, , 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 1, 0, 1, 2, , #, #Example file for working with conditional statement, #, def main():, x,y =2,8, if(x < y):, st= "x is less than y", print(st), if __name__ == "__main__":, main(), , Run, Code Line 5: We define two variables x, y = 2, 8, Code Line 7: The if Statement in Python checks for condition x<y which is True in this, case, Code Line 8: The variable st is set to “x is less than y.”

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Code Line 9: The line print st will output the value of variable st which is “x is less than, y”,, , What happen when “if condition” does not meet, In this step, we will see what happens when if condition in Python does not meet., , Code Line 5: We define two variables x, y = 8, 4, Code Line 7: The if Statement in Python checks for condition x<y which is False in this, case, Code Line 8: The variable st is NOT set to “x is less than y.”, Code Line 9: The line print st – is trying to print the value of a variable that was never, declared. Hence, we get an error.

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How to use “else condition”, The “else condition” is usually used when you have to judge one statement on the basis of, other. If one condition goes wrong, then there should be another condition that should, justify the statement or logic., Example:, , This code is editable. Click Run to Execute, , 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 1, 0, 1, 1, 2, 1, 3, , #, #Example file for working with conditional statement, #, def main():, x,y =8,4, if(x < y):, st= "x is less than y", else:, st= "x is greater than y", print (st), if __name__ == "__main__":, main()

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Run, Code Line 5: We define two variables x, y = 8, 4, Code Line 7: The if Statement in Python checks for condition x<y which is False in this, case, Code Line 9: The flow of program control goes to else condition, Code Line 10: The variable st is set to “x is greater than y.”, Code Line 11: The line print st will output the value of variable st which is “x is greater, than y”,, , When “else condition” does not work, There might be many instances when your “else condition” won’t give you the desired result., It will print out the wrong result as there is a mistake in program logic. In most cases, this, happens when you have to justify more than two statement or condition in a program., An example will better help you to understand this concept., Here both the variables are same (8,8) and the program output is “x is greater than y”, which, is WRONG. This is because it checks the first condition (if condition in Python), and if it fails,, then it prints out the second condition (else condition) as default. In next step, we will see, how we can correct this error.

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This code is editable. Click Run to Execute, , 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 1, 0, 1, 1, 2, 1, 3, 4, , #, #Example file for working with conditional statement, #, def main():, x,y =8,8, if(x < y):, st= "x is less than y", else:, st= "x is greater than y", print(st), if __name__ == "__main__":, main(), , Run

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How to use “elif” condition, To correct the previous error made by “else condition”, we can use “elif” statement. By using, “elif” condition, you are telling the program to print out the third condition or possibility, when the other condition goes wrong or incorrect., Example, , This code is editable. Click Run to Execute, , 1, 2, 3, 4, 5, 6, 7, 8, 9, , #, #Example file for working with conditional statement, #, def main():, x,y =8,8, if(x < y):, st= "x is less than y"

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1, elif (x == y):, 1, 0, st= "x is same as y", 1, 1, 2, else:, 1, 3, st="x is greater than y", 1, 4, print(st), 1, 5, 1, 6 if __name__ == "__main__":, 1, 7, main(), 8, Run, Code Line 5: We define two variables x, y = 8, 8, Code Line 7: The if Statement checks for condition x<y which is False in this case, Code Line 10: The flow of program control goes to the elseif condition. It checks, whether x==y which is true, Code Line 11: The variable st is set to “x is same as y.”, Code Line 15: The flow of program control exits the if Statement (it will not get to the, else Statement). And print the variable st. The output is “x is same as y” which is correct, , How to execute conditional statement with minimal code, In this step, we will see how we can condense out the conditional statement. Instead of, executing code for each condition separately, we can use them with a single code., Syntax, , A If B else C, , Example:

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This code is editable. Click Run to Execute, , 1, 2 def main():, 3, x,y = 10,8, 4, st = "x is less than y" if (x < y) else "x is greater tha, 5, print(st), 6, 7 if __name__ == "__main__":, 8, main(), Run, Code Line 2: We define two variables x, y = 10, 8, Code Line 3: Variable st is set to “x is less than y “if x<y or else it is set to “x is greater, than or equal to y”. In this x>y variable st is set to “x is greater than or equal to y.”, Code Line 4: Prints the value of st and gives the correct output, Instead of writing long code for conditional statements, Python gives you the freedom, to write code in a short and concise way., , Python Nested if Statement, Following example demonstrates nested if Statement Python, This code is editable. Click Run to Execute, , 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 1, 0, 1, 1, 2, 1, 3, 1, 4, 1, 5, 1, 6, 7, , total = 100, #country = "US", country = "AU", if country == "US":, if total <= 50:, print("Shipping, elif total <= 100:, print("Shipping, elif total <= 150:, print("Shipping, else:, print("FREE"), if country == "AU":, if total <= 50:, print("Shipping, else:, print("FREE"), , Cost is, , $50"), , Cost is $25"), Costs $5"), , Cost is, , $100")

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Run, Uncomment Line 2 in above code and comment Line 3 and run the code again, , Switch Case Statement in Python, What is Switch statement?, A switch statement is a multiway branch statement that compares the value of a variable to, the values specified in case statements., Python language doesn’t have a switch statement., Python uses dictionary mapping to implement Switch Case in Python, Example, , function(argument){, switch(argument) {, case 0:, return "This is Case Zero";, case 1:, return " This is Case One";, case 2:, return " This is Case Two ";, default:, return "nothing";, };, };, , For the above Switch case in Python, , def SwitchExample(argument):, switcher = {, 0: " This is Case Zero ",

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1: " This is Case One ",, 2: " This is Case Two ",, }, return switcher.get(argument, "nothing"), , if __name__ == "__main__":, argument = 1, print (SwitchExample(argument)), , Python 2 Example, Above codes are Python 3 examples, If you want to run in Python 2 please consider following, code., , # If Statement, #Example file for working with conditional statement, #, def main():, x,y =2,8, if(x < y):, st= "x is less than y", print st, if __name__ == "__main__":, main(), , # How to use "else condition", #Example file for working with conditional statement, #, def main():, x,y =8,4, if(x < y):, st= "x is less than y"

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else:, st= "x is greater than y", print st, if __name__ == "__main__":, main(), , # When "else condition" does not work, #Example file for working with conditional statement, #, def main():, x,y =8,8, if(x < y):, st= "x is less than y", else:, st= "x is greater than y", print st, if __name__ == "__main__":, main(), , # How to use "elif" condition, #Example file for working with conditional statement, #, def main():, x,y =8,8, if(x < y):, st= "x is less than y", elif (x == y):, st= "x is same as y", else:, st="x is greater than y", print st

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if __name__ == "__main__":, main(), , # How to execute conditional statement with minimal code, def main():, x,y = 10,8, st = "x is less than y" if (x < y) else "x is greater than or, equal to y", print st, if __name__ == "__main__":, main(), , # Nested IF Statement, total = 100, #country = "US", country = "AU", if country == "US":, if total <= 50:, print "Shipping Cost is, , $50", , elif total <= 100:, print "Shipping Cost is $25", elif total <= 150:, print "Shipping Costs $5", else:, print "FREE", if country == "AU":, if total <= 50:, print "Shipping Cost is, else:, print "FREE", , #Switch Statement, def SwitchExample(argument):, switcher = {, 0: " This is Case Zero ",, , $100"

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1: " This is Case One ",, 2: " This is Case Two ",, }, return switcher.get(argument, "nothing"), , if __name__ == "__main__":, argument = 1, print SwitchExample(argument), , Summary:, A conditional statement in Python is handled by if statements and we saw various other, ways we can use conditional statements like Python if else over here., “if condition” – It is used when you need to print out the result when one of the, conditions is true or false., “else condition”- it is used when you want to print out the statement when your one, condition fails to meet the requirement, “elif condition” – It is used when you have third possibility as the outcome. You can use, multiple elif conditions to check for 4th,5th,6th possibilities in your code, We can use minimal code to execute conditional statements by declaring all condition, in single statement to run the code, Python If Statement can be nested, , You Might Like:, Python TUPLE – Pack, Unpack, Compare, Slicing, Delete, Key, Python Check if File Exists: How to Check If a Directory Exists?, PyTest Tutorial: What is, How to Install, Framework, Assertions, Python round() function with EXAMPLES, Python Not Equal (!=) Operator with Examples, , Prev, , Report a Bug, , Next