For

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	Practical Programming in Tcl & Tk, Third Edition By Brent B. Welch
	Table of Contents
	Chapter 6.  Control Structure Commands

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For

The for command is similar to the C for statement. It takes four arguments:

 for initial test final body 

The first argument is a command to initialize the loop. The second argument is a boolean expression that determines whether the loop body will execute. The third argument is a command to execute after the loop body:

Example 6-13 A for loop.

 for {set i 0} {$i < 10} {incr i 3} {    lappend aList $i } set aList => 0 3 6 9 

You could use for to iterate over a list, but you should really use foreach instead. Code like the following is slow and cluttered:

 for {set i 0} {$i < [llength $list]} {incr i} {     set value [lindex $list $i] } 

This is the same as:

 foreach value $list { } 

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