Programming structures

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Loops

uprepa(n){...instructions...}
repeats the instructions between curly brackets exactly n times.

Example:

# a square of 2x2
uprepa(4)
{
    framåt(2)
    höger()
}
                  

uprepa(){...instructions...}
just keeps repeating the instructions between curly brackets for ever.

Example:

# just goes forward
# (but eventually will stay hitting a wall)
uprepa()
{
    framåt()
}

uprepaMedan(condition){...instructions...}
repeats the instructions between curly brackets as long as the condition holds. This condition must be a perception/seeing instruction (for example framåtÄrOhindrat)

Example:

# keeps going forward, 
# but stops when it can't go any further
uprepaMedan(framåtÄrHinder)
{
    framåt(1)
}

avbryt
allows you to jump out of the loop (e.g. a repeat() section) so it stops performing the instructions between curly brackets. The robot will resume performing the instructions left after the closing curly bracket of the loop.

Example:

# keep going forward, until yu can't go any further
uprepa()
{
    om(framåtÄrHinder())
    {    
        avbryt
    }
    annars
    {    
        framåt(1)
    }
}
                  

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If-structures

om(condition){...instructions...}
will perform the the instructions between curly brackets, only if the condition holds. Else the robot immediatly steps to the instructions written after the closing curly bracket.The condtion must be a perception/seeing instruction (for example: framåtÄrOhindrat())

Example:

# if you see white paint on your left, make it black
om(vänsterÄrVit())
{
    vänster()    
    framåt(1)
    målaSvart()
    slutaMåla()
    backåt(1)
    höger()
}
                  

om(condition){...instructions...}annars{...instructions...}
will perform the the instructions between the first pair of curly brackets, only if the condition holds. Then it will not perform the instructions of the else block (second pair of instructions). When the condition does not hold, the robot will only perform the instructions in between the second pair of curly brackets. After it performed one of the instruction blocks, it will read the instructions after the last curly bracket.The condtion must be a perception/seeing instruction (for example: framåtÄrOhindrat())

Example:

# if you see white paint on your left, make it black
# else drive a few steps forward
om(vänsterÄrVit())
{
    vänster()    
    framåt(1)
    målaSvart()
    slutaMåla()
    backåt(1)
    höger()
}
annars
{
    framåt(3)
}
                  

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Logical
expressions

The conditions of if- and repeatWhile-structures is a so-called logical expression. Such an expression will result in the value sant or falskt, which is then used to decide to step to the appropriate part of the code to resume execution.

A logical expression can be a perception instruction, e.g.: sant(). Basic instructions may also be composed with the boolean operators ~, &, |.

Example:

om(vänsterÄrVit())
{
    vänster()    
    framåt(1)    
}

The condition can however also be refined to more indicate more precisely when the corresponding instructions should be executed by using (a combination of) the following operators.

The values sant and falskt can also be applied directly as if it was a perception instruction.

The order of the operators is of importance (just like multiplying and adding numbers). The operation ~ binds strongest, followed by &, followede by |. Brackets can be used to influence the order of evaluation.

Examples:

				
uprepaMedan(inte framåtÄrOhindrat() och (vänsterÄrVit() eller högerÄrVit())){
    framåt(1)
}

om(kastaSlant() och inte högerÄrVit())
{
    höger()
    backåt(1)
}

om(sant och falskt){
    framåt(1)
}
              

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Procedures

procedur name(par1, par2, ... , parN){...instructions...}
defines a new procedure with the name you want. The procedure can have zero or more parameters, which you may also give useful names. Here they are called par1, par2, . . . , parN. These are the variables you can use in the instruction beteen curly brackets. The code in a procedure will not be performed automatically, you have to write a 'procedure call' every time you want to perform the instructions in the definition (See next instruction).
Tip: create a new procedure when when you you use a sequence of instructions more than once.

Example:

# define how to draw a rectangle
procedur rectangle(width, height)
{
    målaVit()
    uprepa(2)
    {
        framåt(height)
        höger()
        framåt(width)
        höger()
    }
    slutaMåla()
}                  

name(arg1, arg2, . . . , argN)
is the call to the procedure with the corresponding name and the same amount parameters as you have arguments. The argument, here called arg1, arg2, . . . , argN, are the particular values that will be used in the procedure definition.

Example:

# these instructions will be performed
framåt(1)
rectangle(3,2) # a call to the 'rectangle' procedur
framåt(3)
rectangle(1,4) # another call with other arguments


# this is the definition of 'rectangle'
procedur rectangle(width, height)
{
    målaVit()
    uprepa(2)
    {
        framåt(height)
        höger()
        framåt(width)
        höger()
    }
    slutaMåla()
}