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10.2: Pseudocode Examples for Control Structures

  • Page ID
    11288
  • \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

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    \( \newcommand{\vectorAt}[1]{\vec{\text{#1}}}      % arrow\)

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    Overview

    No standard for pseudocode syntax exists. However, there are some commonly followed conventions to help make pseudocode written by one programmer easily understood by another programmer. Most of these conventions follow two concepts:

    • Use indentation to show the action part of a control structure
    • Use an ending phrase word to end a control structure

    The sequence control structure simply lists the lines of pseudocode. The concern is not with the sequence category but with selection and two of the iteration control structures. The following are commonly used ending phrase-words:

    Control Structure Ending Phrase Word
    If then Else Endif
    Case Endcase
    While Endwhile
    For Endfor

    The Do While and Repeat Until iteration control structures don't need an ending phrase-word. We simply use the first word, then the action part, followed by the second word with the test expression. Here are some examples:

    Selection Control Structures

    Pseudocode: If then Else
    If age > 17
      Display a message indicating you can vote.
    Else
      Display a message indicating you can't vote.
    Endif 
    
    Pseudocode: Case
    Case of age
      0 to 17   Display "You can't vote."
      18 to 64  Display "You're in your working years."
      65 +      Display "You should be retired."
    Endcase 
    

    Iteration (Repetition) Control Structures

    Pseudocode: While
    count assigned zero
    While count < 5
      Display "I love computers!"
      Increment count
    Endwhile 
    
    Pseudocode: For
    For x starts at 0, x < 5, increment x
      Display "Are we having fun?"
    Endfor 
    
    Pseudocode: Do While
    count assigned five
    Do
      Display "Blast off is soon!"
      Decrement count
    While count > zero 
    
    Pseudocode: Repeat Until
    count assigned five
    Repeat
      Display "Blast off is soon!"
      Decrement count
    Until count < one 
    

    This page titled 10.2: Pseudocode Examples for Control Structures is shared under a CC BY license and was authored, remixed, and/or curated by Kenneth Leroy Busbee (OpenStax CNX) .

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