Pseudocode

 ( Articles With Example Pseudocode ) 

In computer science, pseudocode is a description of the steps in an algorithm using a mix of conventions of programming languages (like assignment operator, conditional operator, loop) with informal, usually self-explanatory, notation of actions and conditions.An often-repeated definition of pseudocode since at least 2003 is "a detailed yet readable description of what a computer program or algorithm must do, expressed in a formally-styled natural language" Although pseudocode shares features with regular programming languages, it is intended for human reading rather than machine control. Pseudocode typically omits details that are essential for machine implementation of the algorithm, meaning that pseudocode can only be verified by hand.

No broad standard for pseudocode syntax exists, as a program in pseudocode is not an executable program; however, certain limited standards exist (such as for academic assessment). Pseudocode resembles skeleton programs, which can be compiler without errors. , DRAKON and Unified Modelling Language (UML) charts can be thought of as a graphical alternative to pseudocode, but need more space on paper. Languages such as HAGGIS bridge the gap between pseudocode and code written in programming languages.

Programmer frequently begin implementing an unfamiliar algorithm by drafting it in pseudocode, then translating it into a programming language while adapting it to fit the larger program. This top-down structuring approach often starts with a pseudocode sketch refined into executable code. Pseudocode is also used in standardization; for example, the MPEG standards rely on formal C-like pseudocode, these standards cannot be understood without grasping the details of the code.

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".

 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
     

 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;
 }
     

 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
     

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

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.

'''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''' ''G''''E'' '''do'''
        ''f''(''u'', ''v'') ← 0
        ''f''(''v'', ''u'') ← 0
     

    '''while''' there exists a path ''p'' from ''s'' to ''t'' '''in''' the residual network ''G''''f'' '''do'''
        let ''c''''f'' be the flow capacity of the residual network ''G''''f''
        ''c''''f''(''p'') ← min{''c''''f''(''u'', ''v'') | (''u'', ''v'') '''in''' ''p''}
        '''for each''' edge (''u'', ''v'') '''in''' ''p'' '''do'''
            ''f''(''u'', ''v'') ←  ''f''(''u'', ''v'') + ''c''''f''(''p'')
            ''f''(''v'', ''u'') ← −''f''(''u'', ''v'')
     

    '''return''' ''f''
     

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
• Flowchart
• Literate programming
• Program Design Language
• Short Code
• Structured English

• Justin Zobel (2025). 9781852338022, Springer. . ISBN 9781852338022
• Wolfgang Reisig (2025). 9783540741077, Springer Berlin Heidelberg. ISBN 9783540741077
• (1996). 9780412087714, Springer US. ISBN 9780412087714

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