Line Numbers and GOTOs
In "unstructured" programming languages such as BASIC and Fortran, line numbers were used to specify the targets of branching statements. For example:
10 IF X = 42 GOTO 40 20 X = X + 1 30 GOTO 10 40 PRINT "X is finally 42!"GOTO-style branching is now widely considered by programmers to be poor programming style, as it tends to lead to the development of spaghetti code. (See Considered harmful, Structured programming.) Even in some later versions of BASIC that still mandated line numbers, the use of line number-controlled GOTOs was phased out whenever possible in favor of cleaner constructs such as the for loop and while loop.
Many modern languages (including C and C++) include a version of the GOTO statement; however, in these languages the target of a GOTO is specified by a line label instead of a line number, and the use of GOTO is strongly discouraged by most programming style guides. The typically accepted use being when it is used to escape out of deep looping. For example:
while(1) { while (1) { if (done) { goto freedom; } } } freedom:This is much cleaner than the alternative that follows, which needs to have a much more widely scoped `done` variable.
while(1) { while (1) { if (done) { break; } } if (done) { break; } }Read more about this topic: Line Number
Famous quotes containing the words line and/or numbers:
“Their bodies are buried in peace; but their name liveth for evermore.”
—Apocrypha. Ecclesiasticus, 44:14.
The line “their name liveth for evermore” was chosen by Rudyard Kipling on behalf of the Imperial War Graves Commission as an epitaph to be used in Commonwealth War Cemeteries. Kipling had himself lost a son in the fighting.
“The land cannot be cleansed of the blood that is shed therein, but by the blood of him that shed it.”
—Bible: Hebrew Numbers 35:33.