break(3tcl) [debian man page]

break(3tcl)						       Tcl Built-In Commands						       break(3tcl)

__________________________________________________________________________________________________________________________________________________

NAME

       break - Abort looping command

SYNOPSIS

       break
_________________________________________________________________

DESCRIPTION

       This command is typically invoked inside the body of a looping command such as for or foreach or while.	It returns a TCL_BREAK code, which
       causes a break exception to occur.  The exception causes the current script to be aborted out to the  innermost	containing  loop  command,
       which  then aborts its execution and returns normally.  Break exceptions are also handled in a few other situations, such as the catch com-
       mand, Tk event bindings, and the outermost scripts of procedure bodies.

EXAMPLE

       Print a line for each of the integers from 0 to 5:
	      for {set x 0} {$x<10} {incr x} {
		 if {$x > 5} {
		    break
		 }
		 puts "x is $x"
	      }

SEE ALSO

       catch(3tcl), continue(3tcl), for(3tcl), foreach(3tcl), return(3tcl), while(3tcl)

KEYWORDS

       abort, break, loop

Tcl																       break(3tcl)

while(3tcl)						       Tcl Built-In Commands						       while(3tcl)

__________________________________________________________________________________________________________________________________________________

NAME

       while - Execute script repeatedly as long as a condition is met

SYNOPSIS

       while test body
_________________________________________________________________

DESCRIPTION

       The  while  command evaluates test as an expression (in the same way that expr evaluates its argument).	The value of the expression must a
       proper boolean value; if it is a true value then body is executed by passing it to the Tcl interpreter.	Once body has been  executed  then
       test  is  evaluated again, and the process repeats until eventually test evaluates to a false boolean value.  Continue commands may be exe-
       cuted inside body to terminate the current iteration of the loop, and break commands may be executed inside body to cause immediate  termi-
       nation of the while command.  The while command always returns an empty string.

       Note: test should almost always be enclosed in braces.  If not, variable substitutions will be made before the while command starts execut-
       ing, which means that variable changes made by the loop body will not be considered in the expression.  This is	likely	to  result  in	an
       infinite loop.  If test is enclosed in braces, variable substitutions are delayed until the expression is evaluated (before each loop iter-
       ation), so changes in the variables will be visible.  For an example, try the following script with and without the braces around $x<10:
	      set x 0
	      while {$x<10} {
		  puts "x is $x"
		  incr x
	      }

EXAMPLE

       Read lines from a channel until we get to the end of the stream, and print them out with a line-number prepended:
	      set lineCount 0
	      while {[gets $chan line] >= 0} {
		  puts "[incr lineCount]: $line"
	      }

SEE ALSO

       break(3tcl), continue(3tcl), for(3tcl), foreach(3tcl)

KEYWORDS

       boolean value, loop, test, while

Tcl																       while(3tcl)