Add Palindromic Number in Tcl (#5073)

Author: pascalecu

archive/t/tcl/palindromic-number.tcl

@@ -0,0 +1,30 @@
+package require Tcl 8.6
+
+proc usage {} {
+    puts stderr "Usage: please input a non-negative integer"
+    exit 1
+}
+
+proc isNonNegativeInteger {s} { return [regexp {^[0-9]+$} $s] }
+
+
+proc isPalindrome {s} {
+    set n [string length $s]
+    set i 0
+    set j [expr {$n - 1}]
+    while {$i < $j} {
+        if {[string range $s $i $i] ne [string range $s $j $j]} {
+            return 0
+        }
+        incr i
+        incr j -1
+    }
+    return 1
+}
+
+if {$argc != 1} { usage }
+
+set input [string trim [lindex $argv 0]]
+if {![isNonNegativeInteger $input]} { usage }
+
+puts [expr {[isPalindrome $input] ? "true" : "false"}]