Page 297 - AI Ver 1.0 Class 9
P. 297

SyntaxError: EOL while scanning string literal

              a = 5
              b = 10
              c = a + b
              SyntaxError: unexpected indent
              print("Python"))
              SyntaxError: unmatched ')'

            Logical Error
            This kind of error is difficult to find since the program will run correctly but the desired output is not achieved.
            This happens if we give a wrong formula for the calculation to be done, write wrong logic for the problem to be
            solved through the code. For example,

            To calculate the average:
              p = marks1 + marks2 / 2  #instead of (marks1+marks2) / 2
            Preceding code produces a wrong output due to the logical error in formula. Let us take another example. To
            find the perimeter of rectangle,

              p = 2 * l + b            #instead of p = 2 * (l + b)

            Runtime Error
            Runtime error occurs during the execution of a program like wrong input or output errors, undefined object
            errors, division by zero errors. This type of error will halt the program execution unexpectedly.
            Example of runtime error is:
              a = int(input("enter first number"))
              b = int(input("enter second number"))
              c = a / b
            If a = 5 and b = 0, then it will display:
               ZeroDivisionError: division by zero


                    Control Statements

            As you know that a program is a set of instructions given to a computer to do a specific task. The order of
            execution of these instructions controls the flow of a program. There are three important ways to control the
            flow of a program which are interpreted by any programming language in a structured manner. These are:
               • Sequential
               • Selection
               • Iterative
            Let us learn about these in detail.


                    Sequential Statements

            A step-by-step process of execution of code is called sequential flow of control. This is the default flow of
            execution of a program. It means that the computer will run the code one line at a time starting from line 1,
            followed by line 2 and so on till it reaches the last line of the program.
            Let us take an example of making a mango smoothie. The steps will be:
            1.  Put mango pieces in a Mixer jar
            2.  Add sugar

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