THE GOTO STATEMENT

THE  GOTO STATEMENT

C supports the goto statement to branch unconditionally from one point to another in the program. Although it may not be essential to use the goto statement in a highly structured language like C, there may be occations when the use of goto might be desirable. The goto requires a label in a order to identify the place where the branch is to be made. A label is any valid variable name, and must be followed by a colon. The label is placed immediately before the statement where the control is to transferred. Before goto statement. if condition must be added. The general forms of goto and label statements are shown below:

Forward jump                                                          Backward jump

if(test expression)

goto label;                                                                    label:

...............                                                                      statement;

...............                                                                      .............

...............                                                                      ..............

label:                                                                            if(test expression)

statement;                                                                  goto label;

The label: can be anywhere in the program either before or after the goto label; statement. During the running of a program when a statement like  goto begin; is met, the flow of control will jump to the statement immediately following the label begin:.Note that a goto breaks the normal sequential execution of the program. If the label: is before the statement goto label; a loop will be formed and some statements will be executed repeatedly. Such a jump is known as backward jump. On the other hand, if the label: is placed after the goto label; some statements will be skipped and the jump is known as a forward jump. A goto is often used at the end of a program to direct the control to go  to the input statement, to read further data. Consider the following example:

main()

{

double x, y;

read:

scanf(“%lf”, &x);

if(x < 0)

goto read;

y = sqrt(x);

printf(“%lf\n”, y)