Characters within braces are passed to a command exactly as written. Curly braces are used to define a block that’s deferred – in other words, it may be run AFTER the rest of the command on the current line. Here we will see an example of “info exists”.Ĭurly braces in TCL group words together to become arguments. There are various “info” command in TCL like “info exists”, “info functions”, “info global”, and so on. The “info exists” command returns 1 if varName exists as a variable (or an array element) in the current context, otherwise returns 0. The unset command is used to destroy a variable. The “set” command is used to create and read variables as shown above.
So we get the value of variable ‘a’ as 10. To obtain the value of variable have to use “$” symbol like To create variables in TCL, you need to use “set” command Look at some example for case sensitive variable. It means hello, Hello, HELLO all are different in TCL. Variables are created by “set command” and all variable names are case sensitive. In other words, a variable is a reference to a computer memory, where the value is stored. TCL VariableĪ variable is an identifier which holds a value. All characters after the “#” are ignored by tclsh shell command. NOTE: –To comment any string in TCL “#” is used. In the example below, you can see special character ” “, remains after the backslash. Any character immediately following the backslash will stand without substitution. In Tcl, the backslash is used for escaping special characters as well as for spreading long commands across multiple lines. puts $a : It will print the value of ‘a’ to the console.puts a : It will print string “a” but not the value of ‘a’ to the console.
Here we create a variable called “a” and set value “10” to it. TCL performs variable substitution with the help of $ sign. ”expr” used for performing the arithmetic calculation. Here the command between the square brackets is evaluated first. Square brackets are used for command substitution. There are three kinds of substitutions in TCL
#ACTIVETCL TUTORIAL UPDATE#
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