xHarbour Reference Documentation > Function Reference

IsCntrl()

Checks if the first character of a string is a control character.

Syntax

IsCntrl( <cString> ) --> lIsCtrlChar

Arguments

<cString>

A character string to check for its first character.

Return

The function returns .T. (true) when the leftmost character of a string is a control character, otherwise .F. (false).

Description

The function is used to check if a string begins with a control character. It returns .T. (true) when the ASCII value of the first character is in the range 1-31 or is 127, and .F. (false) when it begins with any other character.

Info

See also:	IsAlNum(), IsAlpha(), IsAscii(), IsDigit(), IsGraph(), IsLower(), IsPrint(), IsPunct(), IsSpace(), IsUpper(), IsXDigit(), Lower(), Upper()
Category:	Character functions , xHarbour extensions
Source:	rtl\is.c
LIB:	xhb.lib
DLL:	xhbdll.dll

Example

// The example demonstrates various results of IsCntrl()

   #define  CRLF    Chr(13)+Chr(10)
   #define  TAB     Chr(9)
   #define  BELL    Chr(7)

   PROCEDURE Main

      ? IsCntrl( "ABC" )               // result: .F.
      ? IsCntrl( "xyz" )               // result: .F.
      ? IsCntrl( "123" )               // result: .F.
      ? IsCntrl( " xHarbour" )         // result: .F.

      ? IsCntrl( CRLF )                // result: .T.
      ? IsCntrl( TAB )                 // result: .T.
      ? IsCntrl( BELL )                // result: .T.

   RETURN