tcl [4]: 循环和分支

最新推荐文章于 2025-03-06 17:00:23 发布

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本文深入探讨TCL编程中的循环结构如for、while，以及条件判断语句if-else，介绍如何在TCL中实现流程控制，提升程序的灵活性和效率。

# <6> 循环
# >>> for loop
# >>> 循环中的为已知变量赋值，都是用set variable value
set number [expr {int (1.2/0.1) }]
for {set i o} {$i <= $number} {incr i} {
	set x [expr {$i*0.1}]
	puts $x
}
# >>> while loop
set x 0.0
set delta 0.1
while {$x < 1.2+0.5*$delta } {
	set x [expr {$x + $delta}]
	puts $x
}

# >>> break : 	结束while循环
# >>> continue: 结束本次循环，进入下一个循环，继续测试continue是否为真

while {$x < 5} {
        set x [expr {$x + 1}]
        if {$x > 7} break
        puts "x is $x"
}
#>>>打印结果>>>
# x is 2
# x is 3
# x is 4
# x is 5

set x 0
while {$x < 5} {
        set x [expr {$x + 1}]
        if {$x > 3} continue
        puts "x is $x"
}
#>>>打印结果>>>
#x is 1
#x is 2
#x is 3


# 分支
# >>> if...else ...elseif
# >>> if {condition} //{}也可省略
set x 1

if {$x == 2} {
	puts "$x is 2"
} else {
	puts "$x is not 2"
}

if {$x != 1} {
    puts "$x is != 1"
} else {
    puts "$x is 1"
}

if {$x==1} {
	puts "GOT 1"
}

# >>> switch 
# >>> 和C语言的switch的差别是，tcl中不仅仅可以对比数字，还可以对比string
set X "ONE"
set y 1
set z ONE
switch $X {
        "$z" {
                set y1 [expr {$y+1}]
                puts "MATCH \$z. $y+$z is $y1"
        }
        ONE {
                set y1 [expr {$y+1}]
                puts "MATCH ONE.$y+ONE is $y1"
        }
        TWO {
                set y1 [expr {$y+2}]
                puts "MATCH TWO.$y+TWO is $y1"
        }
        default {
                puts"$X is NOT A MATCH"
        }
}
#>>>打印结果>>>
# MATCH ONE.1+ONE is 2