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|000060b0| 72 69 6e 67 20 66 69 72 | 73 74 2c 20 74 68 65 6e |ring fir|st, then|
|000060c0| 20 62 61 63 6b 20 74 6f | 20 61 6e 20 69 6e 74 65 | back to| an inte|
|000060d0| 67 65 72 2c 20 61 73 0a | 20 20 54 63 6c 20 63 75 |ger, as.| Tcl cu|
|000060e0| 72 72 65 6e 74 6c 79 20 | 64 6f 65 73 20 69 6d 70 |rrently |does imp|
|000060f0| 6c 69 63 69 74 6c 79 2e | 0a 0a 49 66 20 74 68 69 |licitly.|..If thi|
|00006100| 73 20 73 65 65 6d 73 20 | 6f 76 65 72 6c 79 20 63 |s seems |overly c|
|00006110| 6f 6d 70 6c 65 78 2c 20 | 72 65 63 61 6c 6c 20 74 |omplex, |recall t|
|00006120| 68 61 74 20 54 63 6c 20 | 69 73 20 61 20 74 79 70 |hat Tcl |is a typ|
|00006130| 65 6c 65 73 73 20 6c 61 | 6e 67 75 61 67 65 2e 0a |eless la|nguage..|
|00006140| 20 20 4c 69 73 74 73 2c | 20 62 6f 6f 6c 65 61 6e | Lists,| boolean|
|00006150| 20 65 78 70 72 65 73 73 | 69 6f 6e 73 2c 20 69 6e | express|ions, in|
|00006160| 74 65 67 65 72 73 20 61 | 6e 64 20 73 6f 20 6f 6e |tegers a|nd so on|
|00006170| 20 61 72 65 20 6e 6f 74 | 20 64 69 73 74 69 6e 67 | are not| disting|
|00006180| 75 69 73 68 65 64 20 62 | 79 0a 20 20 54 63 6c 20 |uished b|y. Tcl |
|00006190| 75 6e 74 69 6c 20 69 6e | 64 69 76 69 64 75 61 6c |until in|dividual|
|000061a0| 20 63 6f 6d 6d 61 6e 64 | 73 20 74 68 72 6f 77 20 | command|s throw |
|000061b0| 65 78 63 65 70 74 69 6f | 6e 73 20 62 61 73 65 64 |exceptio|ns based|
|000061c0| 20 6f 6e 20 62 61 64 20 | 64 61 74 61 2e 20 20 54 | on bad |data. T|
|000061d0| 68 65 0a 20 20 66 6f 6c | 6c 6f 77 69 6e 67 20 63 |he. fol|lowing c|
|000061e0| 6f 64 65 20 77 69 74 68 | 20 65 78 65 63 75 74 65 |ode with| execute|
|000061f0| 20 77 69 74 68 6f 75 74 | 20 65 72 72 6f 72 3a 0a | without| error:.|
|00006200| 0a 5c 62 65 67 69 6e 7b | 76 65 72 62 61 74 69 6d |.\begin{|verbatim|
|00006210| 7d 0a 20 20 70 72 6f 63 | 20 63 64 72 20 7b 6c 69 |}. proc| cdr {li|
|00006220| 73 74 7d 20 7b 20 0a 20 | 20 20 20 20 20 72 65 74 |st} { . | ret|
|00006230| 75 72 6e 20 5b 6c 72 61 | 6e 67 65 20 24 6c 69 73 |urn [lra|nge $lis|
|00006240| 74 20 31 20 65 6e 64 5d | 0a 20 20 7d 0a 20 20 73 |t 1 end]|. }. s|
|00006250| 65 74 20 69 20 32 3b 20 | 73 65 74 20 6a 20 33 3b |et i 2; |set j 3;|
|00006260| 20 73 65 74 20 6b 20 22 | 33 20 34 22 0a 20 20 6c | set k "|3 4". l|
|00006270| 69 6e 73 65 72 74 20 22 | 24 6a 20 24 6b 22 20 5b |insert "|$j $k" [|
|00006280| 63 64 72 20 7b 31 20 32 | 7d 5d 20 24 69 24 6a 0a |cdr {1 2|}] $i$j.|
|00006290| 5c 65 6e 64 7b 76 65 72 | 62 61 74 69 6d 7d 0a 0a |\end{ver|batim}..|
|000062a0| 20 20 54 68 65 20 6f 75 | 74 70 75 74 20 6f 66 20 | The ou|tput of |
|000062b0| 74 68 69 73 20 63 6f 6d | 6d 61 6e 64 20 69 73 20 |this com|mand is |
|000062c0| 60 60 33 20 33 20 32 33 | 20 34 27 27 2e 20 20 44 |``3 3 23| 4''. D|
|000062d0| 75 72 69 6e 67 20 74 68 | 65 20 63 6f 75 72 73 65 |uring th|e course|
|000062e0| 20 6f 66 0a 20 20 65 78 | 65 63 75 74 69 6f 6e 20 | of. ex|ecution |
|000062f0| 77 65 20 68 61 76 65 20 | 69 6d 70 6c 69 63 69 74 |we have |implicit|
|00006300| 6c 79 20 63 6f 6e 76 65 | 72 74 65 64 20 66 72 6f |ly conve|rted fro|
|00006310| 6d 20 73 74 72 69 6e 67 | 20 74 6f 20 69 6e 74 65 |m string| to inte|
|00006320| 67 65 72 73 2c 20 73 74 | 72 69 6e 67 73 0a 20 20 |gers, st|rings. |
|00006330| 74 6f 20 6c 69 73 74 73 | 2c 20 6c 69 73 74 73 20 |to lists|, lists |
|00006340| 74 6f 20 69 6e 74 65 67 | 65 72 73 2c 20 61 6e 64 |to integ|ers, and|
|00006350| 20 69 6e 74 65 67 65 72 | 73 20 74 6f 20 73 74 72 | integer|s to str|
|00006360| 69 6e 67 73 2e 20 20 57 | 68 69 6c 65 20 74 68 69 |ings. W|hile thi|
|00006370| 73 20 69 73 0a 20 20 63 | 6c 65 61 72 6c 79 20 6e |s is. c|learly n|
|00006380| 6f 74 20 61 6e 20 65 78 | 61 6d 70 6c 65 20 6f 66 |ot an ex|ample of|
|00006390| 20 67 6f 6f 64 20 63 6f | 64 69 6e 67 20 70 72 61 | good co|ding pra|
|000063a0| 63 74 69 63 65 2c 20 69 | 74 20 69 73 20 6c 65 67 |ctice, i|t is leg|
|000063b0| 61 6c 20 54 63 6c 20 69 | 6e 70 75 74 2c 0a 20 20 |al Tcl i|nput,. |
|000063c0| 61 6e 64 20 69 6e 20 6d | 61 6e 79 20 63 61 73 65 |and in m|any case|
|000063d0| 73 20 73 69 6d 69 6c 61 | 72 20 75 73 61 67 65 73 |s simila|r usages|
|000063e0| 20 6d 61 79 20 61 70 70 | 65 61 72 20 69 6e 20 72 | may app|ear in r|
|000063f0| 65 61 6c 20 73 6f 75 72 | 63 65 20 63 6f 64 65 2e |eal sour|ce code.|
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