Assert Statement in Python for Error Detection
We all are familiar with the word “debugging”. This term includes a variety of steps to debug a given code. One such part is the “assert statement”. In this tutorial, we will learn about the application and implementation of the assert statement in Python to calculate percentage error.
This statement is widely used when we want to imply constraints to the working of the program.
Syntax: assert <Condition>
Error Detection in Python – Assert Statement
Let us suppose that we want to compute the percentage of marks obtained in a subject. It may happen that the values of variables maxmarks and marks entered by the user may not be in proper range. It may be negative or greater than the maximum marks.
Here the assert statement comes handy which checks the fulfilment of input with the set constraints.
Error Detection in Python using assert statement
Here is the source code in Python to detect error in calculation ( Percentage error ) using assert statement
def percent(marks, maxmarks): percentv=(marks/maxmarks)*100 return percentv #main maxmarks=float(raw_input()) #first constraint application using assert statement assert maxmarks>=0 and maxmarks<=500 # here assertion error is raised if the input is not satisfying contraints marks=float(raw_input()) #second contraint application assert marks>=0 and marks<=maxmarks # here assertion error is raised if the input is not satisfying the constraints percentage=percent(marks, maxmarks) print "percentage : ",percentage
Testcase 1: 150 155
Output: Assertion error ; line 13
Testcase 2: 150 50
Output: percentage : 33.3333333333
If both the assertion hold Boolean value True, the function displays percentage as the output as seen in Testcase 2 and in case any of then retains a Boolean value False, then assertion error is raised as seen in Testcase 1.