Add File Input Output in Tcl (#5056)

Author: pascalecu

archive/t/tcl/file-input-output.tcl

@@ -0,0 +1,54 @@
+#!/usr/bin/env tclsh
+
+proc writeToFile {filename} {
+    if {[catch {set fh [open $filename w]} err]} {
+        puts "Error opening file for writing \"$filename\": $err"
+        return 1
+    }
+
+    if {[catch {
+        puts $fh "A line of text"
+        puts $fh "Another line of text"
+        flush $fh
+    } err]} {
+        puts "Error writing to file \"$filename\": $err"
+        close $fh
+        return 1
+    }
+
+    close $fh
+    return 0
+}
+
+proc readFromFile {filename} {
+    if {[catch {set fh [open $filename r]} err]} {
+        puts "Error reading from file \"$filename\": $err"
+        return 1
+    }
+
+    set linesRead 0
+    if {[catch {
+        while {[gets $fh line] >= 0} {
+            puts $line
+            incr linesRead
+        }
+    } err]} {
+        puts "Error reading from file \"$filename\": $err"
+        close $fh
+        return 1
+    }
+
+    if {$linesRead == 0} {
+        puts "(File \"$filename\" is empty)"
+    }
+
+    close $fh
+    return 0
+}
+
+set filename "output.txt"
+if {[ writeToFile $filename] != 0} { exit 1 }
+if {[readFromFile $filename] != 0} { exit 1 }
+
+exit 0
+