Page 79 - iPrime_V2.2_class6
P. 79

USE OF LOOP BLOCKS

                 All the programs or projects developed till now run only once. If you want to run a set of statements
                 more than once, you will either run the code again or write the script again. In Scratch, we can
                 save our time and effort by repeating the code without writing the program again or writing the
                 script again. The automatic running of a set of instructions more than once is called looping. The
                 blocks for looping are given in the Control category.
                 The repeat block is used to run a set of instructions for a specified number of
                 times.



                                 The repeat until block is used to run a set of instructions till a condition is satisfied.


                 The  forever block is used  to  run  a  set of  instructions  continuously until
                 stopped. The instructions inside this block will be executed in a loop until the
                 Stop button        is clicked by the user.

                 The Repeat and Repeat Until blocks can be used to display the table of a number input by the
                 user. The script for the sprite can be like this (using the Repeat Until block). Following is the
                 script for displaying table of a number.




















                                                       Example of a looped script

                 The output of the program will be similar to this.















                                                                Output
                 You can also use the forever and repeat blocks with if...then block.

                 Let us make a small script.
                 Change the sprite to butterfly and change the backdrop to flowers.



                                                                                                                   77
                                                                          Scratch Programming—Game Creation        77
   74   75   76   77   78   79   80   81   82   83   84