TCL关系运算符_代码驿站

下表列出了所有Tcl语言支持的关系运算符。假设变量A=10，变量B=20，则：

操作符	描述	例子
==	检查两个操作数的值是否相等，如果是的话那么条件为真。	(A == B) 不为 true.
!=	检查两个操作数的值是否相等，如果值不相等，则条件变为真。	(A != B) 为 true.
>	检查左边的操作数的值是否大于右操作数的值，如果是的话那么条件为真。	(A > B) 不为 true.
<	检查左边的操作数的值是否小于右操作数的值，如果是的话那么条件为真。	(A < B) 为 true.
>=	如果左操作数的值大于或等于右操作数的值，如果是的话那么条件检查为真	(A >= B) 不为 true.
<=	检查左边的操作数的值是否小于或等于右操作数的值，如果是的话那么条件为真。	(A <= B) 为 true.

例子

试试下面的例子就明白了所有的Tcl语言版本的关系运算符：

#!/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"
}

当编译和执行上面的程序，会产生以下结果：

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

我要分享文章