Constructs as commands

All constructs in C are like commands in TCL.
For instance: if, while, for, foreach

if construct:
Syntax: 'if test body'

Note: If test and body part has many words as to require multiple words, enclose them in braces { }. Enter key (newline or space characters) are escaped inside braces.

Example:
% if 5 {
   puts 4
}

% if { $x > $y} {
   puts $y
} else {
   puts $x
}

Here, 'elseif' and 'else' are like arguments for 'if' command.


while construct:
Syntax: 'while test body'

Example:
% while {$x < $y} {
   set x [expr $x + 1]
   puts $x
}


for construct:
Syntax: 'for init test update body'

Example:
% for {i=0; j=5} {$i < $j} {incr i 2} {
   puts $i
}


foreach construct:
Syntax: 'foreach varname list body'

List can be scalar or list. Also, list can be literal or can contain variables or another list.

Example:
% foreach names {rohit shikhar virat ajinkya} {
   puts $names
}

%set L1 {rohit shikhar virat ajinkya}
% foreach names $L1 {
   puts $names
}
switch case construct:


Syntax: 'switch option varname'

Valid options are: exact, glob, regexp, nocase, matchvar VarName...
No fall through in cases
Default is optional

Example:
%switch name {
   virat {puts "Best batsman in cricket"}
   smith{puts "Best batsman in test cricket"} 
   rohit {puts "Best batsman in T20 cricket"}
   root -
   default {puts "No option selected"}
}

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