File input/output: Difference between revisions
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(Clarified task description so as to encourage didactic examples and discourage uninformative tricks.) |
m (→{{header|Tcl}}: more polish) |
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=={{header|Tcl}}== |
=={{header|Tcl}}== |
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{{works with|tclsh}} |
{{works with|tclsh}} |
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{{works with|eTcl}} |
{{works with|eTcl}} |
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{{works with|wish}} |
{{works with|wish}} |
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{{works with|tixwish}} |
{{works with|tixwish}} |
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{{works with|tclkit}} |
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<lang tcl>set in [open "input.txt" r] |
<lang tcl>set in [open "input.txt" r] |
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set out [open "output.txt" w] |
set out [open "output.txt" w] |
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close $in |
close $in |
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close $out</lang> |
close $out</lang> |
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For larger files, it is better to use the <tt>fcopy</tt> command, though in general this restricts what operations can be performed rather more (only encoding and end-of-line translations are possible |
For larger files, it is better to use the <tt>fcopy</tt> command, though in general this restricts what operations can be performed rather more (only encoding and end-of-line translations are possible — or more general byte-level transformations with the generic filter mechanism provided in Tcl 8.6 — none of which are shown here): |
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<lang tcl>set in [open "input.txt" r] |
<lang tcl>set in [open "input.txt" r] |
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set out [open "output.txt" w] |
set out [open "output.txt" w] |
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close $in |
close $in |
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close $out</lang> |
close $out</lang> |
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Or the minimal version if we don't need any processing of the data at all: |
Or the minimal version if we don't need any processing of the data at all: |
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<lang tcl>file copy input.txt output.txt</lang> |
<lang tcl>file copy input.txt output.txt</lang> |
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===Other key file I/O operations=== |
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;Writing a line to a file<nowiki>:</nowiki> |
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Other File I/O: |
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<lang tcl>#open file for writing |
<lang tcl>#open file for writing |
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set myfile [open "README.TXT" w] |
set myfile [open "README.TXT" w] |
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#close the file |
#close the file |
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close $myfile</lang> |
close $myfile</lang> |
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;Reading a line from a file<nowiki>:</nowiki> |
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<lang tcl>#open file for reading |
<lang tcl>#open file for reading |
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set myfile [open "README.TXT" r] |
set myfile [open "README.TXT" r] |
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