Pseudocode

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In

No broad standard for pseudocode

Pseudocode is commonly used in textbooks and

Pseudocode generally does not actually obey the syntax rules of any particular language; there is no systematic standard form. Some writers borrow style and syntax from control structures from some conventional programming language, although this is discouraged.^[5][6] Some syntax sources include Fortran, Pascal, BASIC, C, C++, Java, Lisp, and ALGOL. Variable declarations are typically omitted. Function calls and blocks of code, such as code contained within a loop, are often replaced by a one-line natural language sentence.

Depending on the writer, pseudocode may therefore vary widely in style, from a near-exact imitation of a real programming language at one extreme, to a description approaching formatted prose at the other.

This flexibility brings both major advantages and drawbacks: on the positive side, no executable programming language "can beat the convenience of inventing new constructs as needed and letting the reader try to deduce their meaning from informal explanations", on the negative, "untested code is usually incorrect".^[7]

procedure fizzbuzz;
  for i := 1 to 100 do
    print_number := true;
    if i is divisible by 3 then begin
      print "Fizz";
      print_number := false;
    end;
    if i is divisible by 5 then begin
      print "Buzz";
      print_number := false;
    end;
    if print_number, print i;
    print a newline;
  end

fizzbuzz() {
  for (i = 1; i <= 100; i++) {
    print_number = true;
    if (i is divisible by 3) {
      print "Fizz";
      print_number = false;
    }
    if (i is divisible by 5) {
      print "Buzz";
      print_number = false;
    }
    if (print_number) print i;
    print a newline;
  }
}

def fizzbuzz():
  for i in range(1,101): 
    print_number = true
    if i is divisible by 3: 
      print "Fizz"
      print_number = false
    if i is divisible by 5:
      print "Buzz"
      print_number = false
    if print_number: print i
    print a newline

In

Return ${\displaystyle \sum _{k\in S}x_{k}}$

Normally non-ASCII typesetting is used for the mathematical equations, for example by means of markup languages, such as TeX or MathML, or proprietary formula editors.

Mathematical style pseudocode is sometimes referred to as pidgin code, for example pidgin ALGOL (the origin of the concept), pidgin Fortran, pidgin BASIC, pidgin Pascal, pidgin C, and pidgin Lisp.

The following is a longer example of mathematical-style pseudocode, for the Ford–Fulkerson algorithm:

algorithm ford-fulkerson is
    input: Graph G with flow capacity c, 
           source node s, 
           sink node t
    output: Flow f such that f is maximal from s to t

    (Note that f(u,v) is the flow from node u to node v, and c(u,v) is the flow capacity from node u to node v)

    for each edge (u, v) in GE do
        f(u, v) ← 0
        f(v, u) ← 0

    while there exists a path p from s to t in the residual network Gf do
        let cf be the flow capacity of the residual network Gf
        cf(p) ← min{cf(u, v) | (u, v) in p}
        for each edge (u, v) in p do
            f(u, v) ←  f(u, v) + cf(p)
            f(v, u) ← −f(u, v)

    return f

Various attempts to bring elements of natural language grammar into computer programming have produced programming languages such as

Several formal specification languages include set theory notation using special characters. Examples are:

• Z notation
• Vienna Development Method Specification Language (VDM-SL).

Some array programming languages include vectorized expressions and matrix operations as non-ASCII formulas, mixed with conventional control structures. Examples are:

• A programming language (APL), and its dialects APLX and A+.
• MathCAD
  .

• Concept programming
• Drakon-chart
• Flowchart
• Literate programming
• Program Design Language
• Short Code
• Structured English

Further reading

• Zobel, Justin (2013). "Algorithms". Writing for Computer Science (Second ed.). Springer.
  ISBN 978-1-85233-802-2
  .
• Roy, Geoffrey G (2006). "Designing and explaining programs with a literate pseudocode". Journal on Educational Resources in Computing. 6 (1). Association for Computing Machinery (ACM): 1.
  S2CID 25810599
  .
• Ulate-Caballero, Bryan Alexander; Berrocal-Rojas, Allan; Hidalgo-Cespedes, Jeisson (2021-10-25). "Concurrent and Distributed Pseudocode: A Systematic Literature Review". 2021 XLVII Latin American Computing Conference (CLEI). IEEE. pp. 1–10.
  ISBN 978-1-6654-9503-5
  .
• Reisig, Wolfgang (2007). "Abstract State Machines for the Classroom". Logics of Specification Languages. Monographs in Theoretical Computer Science. An EATCS Series. Springer Berlin Heidelberg. pp. 15–46.
  ISBN 978-3-540-74107-7
  . Retrieved 2023-10-05.
• Mitchell, Joan L.; Pennebaker, William B.; Fogg, Chad E.; LeGall, Didier J. (1996). "Pseudocode and Flowcharts". MPEG Video Compression Standard. New York, NY: Springer US. pp. 105–116.
  ISBN 978-0-412-08771-4
  .
• Bellamy, Rachel (1994-06-01). "What Does Pseudo-Code Do? A Psychological Analysis of the use of Pseudo-Code by Experienced Programmers". Human-Computer Interaction. 9 (2). Informa UK Limited: 225–246.
  ISSN 0737-0024
  .

External links

Look up pseudocode in Wiktionary, the free dictionary.

• A pseudocode standard
• Collected Algorithms of the ACM
• Pseudocode Guidelines, PDF file.