Page 303 - AI Ver 1.0 Class 9
P. 303

The if…elif…else Statement
            When there are multiple conditions in a program then it is handled by using elif statement. It means if the
            previous condition is not True then try this condition written next to elif. If one condition is True then the
            statements below it will be executed and the rest of the conditions given using elif will be ignored. In case all
            the conditions written with elif are not True, then the statements written just below the else statement will
            be executed. The syntax of the if…elif…else statement is as follows:

            if (condition1):
              Statements 1
            elif (condition2):
              Statements 2
            elif (condition3):
              Statements 3
            ...
            else:
              Statements executed when all above conditions are False
            Where
               • if, else, elif are keywords.
               • condition1, condition2 and condition3, …., can be any expression.

               • statements1, statements2 and statements3 are always indented can be single or a block of statements.

              Program 5:  To input two numbers and an operator from the user. Display the result calculated based on the
              operator entered.

            Algorithm                                                Flowchart
            Start                                                                      START
            Input N1, N2, op

            if op is same as that of ‘+’ then                                       Input N1, N2
                Display N1+N2
            Otherwise, if op is same as that of ‘-’ then                                 Is
                                                                                                       Display
                Display N1-N2                                                        op = "+"?  Yes   N1 + N2
            Otherwise, if op is same as that of ‘*’ then

                Display N1*N2                                                             No
            Otherwise                                                                    Is     Yes    Display
                Display "Wrong operator entered"                                      op = "–"?        N1 – N2
            Stop
                                                                                          No

            Source Code:
                                                                                         Is     Yes    Display
                                                                                     op = "*"?
            N1=int(input("Enter first Number :"))                                                      N1 * N2
            N2=int(input("Enter second Number :"))                                        No

            op=input("Enter an operator(+, –, * only) :")                             Display
                                                                               "Sorry! Invalid Operator"
            if op=="+":

                                                                                       STOP


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