If () Then, Else (block)

If () Then, Else
if <> then{ } else{ } :: control
Category	Control
Type	C
Introduced in	16Dec05 (0.x)

The if () then, else block is a control block and a C block. (It is also sometimes known as an "E" block.) The block checks its boolean condition; if the condition is true, the code held inside the first C (space) will activate; if the condition is false, the code inside the second C will activate.

Prior to Scratch 2.0, this block was known as If (), Else, or

if <>{

}else{

}::control

Example Uses

In programming, a very important part is checking conditions. In Scratch, this is done with the if () block. However, an important part of the "checking conditions" is having another piece of code that runs if the condition is false. While this may be worked around, the If (), Else block makes this simpler. Some common uses:

• Doing the opposite action of the first action if the condition is false

repeat until <touching (edge v)?>
    if <(mouse x) > [0]> then
        move (1) steps
    else
        move (-1) steps
    end
end

• If a Sprite's health is below a certain amount, it dies, otherwise it does something else

when green flag clicked
forever
   if <(health) = [0]> then
        play sound (Failure v) until done
        stop [all v]
    else
        broadcast (attack v)
end

• Easy script changes — if a variable equals a certain value, one thing happens, and if the variable does not equal the value, a different thing happens

if <(answer) = [5]> then
    say [Correct!] for (2) seconds
else
    play sound (failed task v) until done
    stop [all v]
end

• Scripts that are adaptable to changes in conditions (such as a changing variable)

if <touching color [#7092be]?> then
    say [We found water!]
else
    say [ ]
end

Workaround

Main article: List of Block Workarounds

This block can be replicated with the following code:

if <. . .::grey> then
 . . . //condition=true
end
if <not <. . .::grey> > then
 . . . //condition=false
end

or

if <. . .::grey> then
    . . .::grey
    broadcast (continue v)
    stop [this script v]
end
. . .::grey
broadcast (continue v)

Note that this last workaround only works if the condition will not be negated in the middle of the first If () block.

Suggestions

Scratchers have suggested a block that reports the first input if true, otherwise if false, reports the second input.

if <> then [] else []:: operators reporter

This block does exist in some Scratch modifications, such as Snap!. However, it can be worked around with the following code, which only works for numbers:

((true::grey)*<boolean::grey>)+((false::grey)*<not<boolean::grey>>)

or this one, which works for any argument type:

if <boolean::grey> then
set [report v] to (true::grey)
else
set [report v] to (false::grey)
end

See Also

• If () Then