下表列出了所有Tcl語言支持的關係運算符。假設變量A=10，變量B=20，則：

操作符

描述

例子

==

檢查兩個操作數的值是否相等，如果是的話那麼條件爲真。

(A == B) 不爲 true.

!=

檢查兩個操作數的值是否相等，如果值不相等，則條件變爲真。

(A != B) 爲 true.

>

檢查左邊的操作數的值是否大於右操作數的值，如果是的話那麼條件爲真。

(A > B) 不爲 true.

<

檢查左邊的操作數的值是否小於右操作數的值，如果是的話那麼條件爲真。

(A < B) 爲 true.

>=

如果左操作數的值大於或等於右操作數的值，如果是的話那麼條件檢查爲真

(A >= B) 不爲 true.

<=

檢查左邊的操作數的值是否小於或等於右操作數的值，如果是的話那麼條件爲真。

(A <= B) 爲 true.

例子

試試下面的例子就明白了所有的Tcl語言版本的關係運算符：

#!/usr/bin/tclsh

set a 21
set b 10

if { $a == $b } {
puts "Line 1 - a is equal to b\n"
} else {
puts "Line 1 - a is not equal to b\n"
}
if { $a < $b } {
puts "Line 2 - a is less than b\n"
} else {
puts "Line 2 - a is not less than b\n"
}
if { $a > $b } {
puts "Line 3 - a is greater than b\n"
} else {
puts "Line 3 - a is not greater than b\n"
}

Lets change value of a and b

set a 5
set b 20
if { $a <= $b } {
puts "Line 4 - a is either less than or equal to b\n"
}
if { $b >= $a } {
puts "Line 5 - b is either greater than or equal to b\n"
}

當編譯和執行上面的程序，會產生以下結果：

Line 1 - a is not equal to b

Line 2 - a is not less than b

Line 3 - a is greater than b

Line 4 - a is either less than or equal to -b

Line 5 - b is either greater than or equal to a