goto: Goto statement

Package: language

Usage

goto label
  .
  .
  .
label: statement

Parameters

label

The destination label. Label names have the same syntax as variable names and can duplicate the names of existing variables.

statement

The statement executed after the goto statement. It may be any executable statement.

Description

The goto statement interrupts the normal flow of program execution by transferring control to the statement following the label. It may also be used to exit from nested loops where the break statement is not adequate.

Examples

1. The most common use of the goto statement is to branch to an error handler if an abnormal condition is detected.

begin
        for (i=1;  i <= 100;  i += 1)
            for (j=1;  j <= 100;  j += 1)
                for (k=1;  k <= 100;  k += 1)
                    if (pixel[i,j,k] < 0)
                        goto err
                    else
                        total += pixel[i,j,k]

        print ("total = ", total)
        return
err:
        print ("Invalid pixel value at ",i,j,k)
end

Bugs

No checking is done to see if a jump is made into a loop.

See also

break, next