Spaghetti code

Spaghetti code is a pejorative term for a computer program code with a complex and tangled control structure, especially one using many GOTOs, exceptions, threads, or other "unstructured" branching constructs.

It is named such because program flow tends to look like a bowl of spaghetti, i.e. twisted and tangled. Also called kangaroo code because such code has so many jumps in it.

Spaghetti code is an example of an anti-pattern.

Examples

10 dim i 20 i = 0 30 i = i + 1 40 if i <> 10 then goto 90 50 if i = 10 then goto 70 60 goto 30 70 print "Program Completed." 80 end 90 print i & " squared = " & i * 2 100 goto 30 Here is the same code written in a procedural style:

dim i for i = 0 to 10 print i & " squared = " & square(i) next print "Program Completed." function square(i) square = i * i end function The program jumps from one area to another but this jumping is predicable and formal. This is because using for loops and functions are standard ways of providing flow control where the goto statement encourages arbitrary flow control. Though this example is small, real world programs are composed of many lines of code and are difficult to maintain when written in a spaghetti code fashion.

Assembly language

While many assembly languages have a function stack, and apparent function calls, these are just a thin wrapper for the goto statement. They store the original location of the program counter in order to return to it later.

Programs written in higher-level languages with high-level constructs such as for loops (as in the second example above) are often compiled into assembly or machine code. When this process occurs, the high-level constructs are translated into low-level "spaghetti code" which may resemble the first example above in terms of control flow.

See also