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called taking a decision. The statements that are executed on the basis of decisions
taken from a choice are called conditional statements.
The conditional statement used in Scratch is the ‘if’ statement. The ‘if’ statement
has two variants —‘if…then’ and ‘if…then…else’. These statements are provided
in Scratch from control category of blocks. The ‘if…then’ block checks the given
condition. If the condition is true, the code inside the
C (space) will be activated. If the condition is false, the control
will come out of the ‘if…then’ block and move to the next
blocks in the sequence.
Suppose, we want to check whether a person is a senior
citizen or not. The code for this can be defined using
‘if’…then’ as:
But this code does not give an output if the age of the person
is less than or equal to 60 years.
For such situations, when two different outputs are to be
specified for two conditions, we use ‘if…then…else’ block. In
this block, if the condition is true, the code inside the first
C (space) will be activated. If the condition is false, the code
inside the second C (space) will be activated.
SENSING BLOCKS
The blocks in the Sensing category help the selected sprite
to detect the presence of other sprites or other elements on
the stage including the edges of the stage. The blocks in the
Sensing category are colour coded as light blue.
Some of the blocks included in the Sensing category are
shown along side.
The Table below shows some important sensing blocks and
their functions.
Becomes true when the sprite
touches the mouse pointer or
the edge of the stage (defined by
clicking on the drop-down arrow)
Becomes true when the sprite
touches a defined colour
Sensing block
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