Expect Script - For Loop - How to use more than 1 variable

Question

How can I use more than 1 variable in expect script "for loop"? Please help. Thanks in advance.

With one variable:

for {set i 1} {$i < 256} {incr i 1} {

}

How can 2 or 3 variables, say init , condition, increment of i, j, k ? comma, semicolon is not working.

Thanks, Krishna

glenn jackman · Accepted Answer · 2020-08-12T11:14:12.810

Keep in mind that expect is an extension of Tcl. Documentation of Tcl is available.

The syntax of for is:

for start test next body

"start" and "next" are both evaluated as scripts. "test" is an expression

You can do:

for {set i 1; set j 10; set k "x"} {$i < 5 && $j > 0} {incr i; incr j -2; append k x} {
    puts "$i\t$j\t$k"
}

outputs

1   10  x
2   8   xx
3   6   xxx
4   4   xxxx

This is equivalent to the following, so use whatever is most readable.

set i 1
set j 10
set k "x"

while {$i < 5 && $j > 0} {
    puts "$i\t$j\t$k"

    incr i
    incr j -2
    append k x
}

In fact, you can make liberal use of newlines in a for command too

for {
    set i 1
    set j 10
    set k "x"
} {
    $i < 5 && $j > 0 
} {
    incr i
    incr j -2
    append k x
} {
    puts "$i\t$j\t$k"
}

1 Answers1