Loops

Loops and iterators

Previous tutorial: Basic data types

Loops are very important to repeat a specific command or a set of commands multiple times. 05AB1E currently has the following loops:

Current loops and iterators

• F-loop, ranges from 0 to n - 1.
• G-loop, ranges from 1 to n - 1.
• ƒ-loop, ranges from 0 to n.
• E-loop, ranges from 1 to n.
• [-loop, ranges from 0 to infinity. Also known as an infinite loop.
• v-iterator, iterates over each element
• µ-loop, loops until the counter value equals n

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F-loop

• Arity: 1
• Syntax: <num> F <code> }

Parameter	Description
<num>	An integer or a string representation of an integer
<code>	An 05AB1E code snippet

The most common loop that is used in 05AB1E. Ranges from 0 to n - 1 with N as the index variable. The following example sum:

4FNO}

4F         # For N in range(0, 4)         --> this will iterate through [0, 1, 2, 3].
  N        #   Push the current index (N) --> N = 0 in the first run, N = 1 in the second, etc.
   O       #   Sum the entire stack
    }      # Close the for loop           --> The code after this will be run as any other normal code.

What this will do is sum the following (index) numbers: 0 + 1 + 2 + 3 = 6. Try it online!

Tip: Whenever the closing bracket is at the end of the file, you can remove the bracket. The EOF acts like an infinite closing bracket.

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G-loop

• Arity: 1
• Syntax: <num> G <code> }

Parameter	Description
<num>	An integer or a string representation of an integer
<code>	An 05AB1E code snippet

A loop very similar to the F-loop, but starts at 1 rather than 0. Ranges from 1 to n - 1 with N as the index variable.

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ƒ-loop

• Arity: 1
• Syntax: <num> ƒ <code> }

Parameter	Description
<num>	An integer or a string representation of an integer
<code>	An 05AB1E code snippet

Also a loop very similar to the F-loop, but end at n rather than n - 1. Ranges from 0 to n with N as the index variable.

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E-loop

• Arity: 1
• Syntax: <num> E <code> }

Parameter	Description
<num>	An integer or a string representation of an integer
<code>	An 05AB1E code snippet

Also a loop very similar to the F or ƒ loops, but start at 1 and end at n instead. Ranges from 1 to n with N as the index variable.

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[-loop

• Arity: 0
• Syntax: [ <code> ]

Parameter	Description
<code>	An 05AB1E code snippet

Also known as an infinite loop. Ranges from 0 till infinity. To break out of the loop, you can use the # (break if true). This would convert the infinite loop to a loop similar like a while(condition) loop. Uses N as the index variable.

For example, if we want to print all numbers until N is 10, we can do the following:

[N,N10Q#

[             # Start the infinite loop
 N,           #   Print N with a newline
   N10Q       #   Check if N equals 10
       #      #   If true: break out of the loop

This prints the numbers 0, 1, 2, ..., 9, 10. Try it online!

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v-iterator

• Arity: 1
• Syntax: <object> v <code> }

Parameter	Description
<object>	An object with type int, str or list
<code>	An 05AB1E code snippet

Iterates through each element/character of the object. Uses N as the current index number and y as the current element. Acts in the same way as the F-loop.

For example, if we want to enumerate each character in the string abcdef and print it like this: <char>: <index>, we can do something like this:

"abcdef"vy?": "?N,

"abcdef"               # Push the string 'abcdef' onto the stack
        v              # Iterate through each element in that string and do the following:
         y?            #   Print the current character without a newline
           ": "?       #   Print the string ': ' without a newline
                N,     #   Print the current index number with a newline

Let's check it out: Try it online!

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µ-loop

• Arity: 1
• Syntax: <num> µ <code> }

Parameter	Description
<num>	An integer or a string representation of an integer
<code>	An 05AB1E code snippet

Loops until the counter variable reaches the provided <num> value.

The counter variable starts at 0, and can be modified using the following commands:

• ¼: increments the counter variable
• ½: pop a, and increments the counter variable if a is true (a == 1)

Tip: 05AB1E automatically puts a ½ command at the end of the provided <code> if it doesn't contain a counter modifying command