TCL允許使用一個(gè)循環(huán)內(nèi)的另一個(gè)循環(huán)。下面的內(nèi)容展示幾個(gè)例子來說明這個(gè)概念。
Tcl語言的嵌套的循環(huán)語句的語法如下:
for {initialization} {condition} {increment} { for {initialization} {condition} {increment} { statement(s); } statement(s); }
Tcl語言嵌套while循環(huán)語句的語法如下:
while {condition} { while {condition} { statement(s); } statement(s); }
在循環(huán)嵌套最后需要說明的是,可以把任何類型循環(huán)嵌套在其他類型循環(huán)內(nèi)。例如,for循環(huán)可以是一個(gè)while循環(huán)的內(nèi)循環(huán),或反之亦然。
下面的程序使用嵌套for循環(huán)從2至100找出所有的素?cái)?shù):
#!/usr/bin/tclsh set j 0; for {set i 2} {$i<100} {incr i} { for {set j 2} {$j <= [expr $i/$j] } {incr j} { if { [expr $i%$j] == 0 } { break } } if {$j >[expr $i/$j] } { puts "$i is prime" } }
當(dāng)上述代碼被編譯和執(zhí)行時(shí),它產(chǎn)生了以下結(jié)果:
2 is prime 3 is prime 5 is prime 7 is prime 11 is prime 13 is prime 17 is prime 19 is prime 23 is prime 29 is prime 31 is prime 37 is prime 41 is prime 43 is prime 47 is prime 53 is prime 59 is prime 61 is prime 67 is prime 71 is prime 73 is prime 79 is prime 83 is prime 89 is prime 97 is prime