下表列出了所有Tcl語言支持的關(guān)系運算符。假設(shè)變量A=10,變量B=20,則:
操作符 | 描述 | 例子 |
---|---|---|
== | 檢查兩個操作數(shù)的值是否相等,如果是的話那么條件為真。 | (A == B) 不為 true. |
!= | 檢查兩個操作數(shù)的值是否相等,如果值不相等,則條件變?yōu)檎妗?/td> | (A != B) 為 true. |
> | 檢查左邊的操作數(shù)的值是否大于右操作數(shù)的值,如果是的話那么條件為真。 | (A > B) 不為 true. |
< | 檢查左邊的操作數(shù)的值是否小于右操作數(shù)的值,如果是的話那么條件為真。 | (A < B) 為 true. |
>= | 如果左操作數(shù)的值大于或等于右操作數(shù)的值,如果是的話那么條件檢查為真 | (A >= B) 不為 true. |
<= | 檢查左邊的操作數(shù)的值是否小于或等于右操作數(shù)的值,如果是的話那么條件為真。 | (A <= B) 為 true. |
試試下面的例子就明白了所有的Tcl語言版本的關(guān)系運算符:
#!/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(dāng)編譯和執(zhí)行上面的程序,會產(chǎn)生以下結(jié)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