TCL關係運算子 - tw511教學網

下表列出了所有Tcl語言支援的關係運算子。假設變數A=10，變數B=20，則：

操作符	描述	例子
==	檢查兩個運算元的值是否相等，如果是的話那麼條件為真。	(A == B) 不為 true.
!=	檢查兩個運算元的值是否相等，如果值不相等，則條件變為真。	(A != B) 為 true.
>	檢查左邊的運算元的值是否大於右運算元的值，如果是的話那麼條件為真。	(A > B) 不為 true.
<	檢查左邊的運算元的值是否小於右運算元的值，如果是的話那麼條件為真。	(A < B) 為 true.
>=	如果左運算元的值大於或等於右運算元的值，如果是的話那麼條件檢查為真	(A >= B) 不為 true.
<=	檢查左邊的運算元的值是否小於或等於右運算元的值，如果是的話那麼條件為真。	(A <= B) 為 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子：

#!/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式，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