ch25.htm

this is a book on pearl , simple example with explanation is given here. it could be beneficial for

<LI><A HREF="#warnLIST">

warn ([LIST])</A>

<LI><A HREF="#writeFILEHANDLEEXPR">

write ([FILEHANDLE | EXPR])</A>

</UL>

</UL>



<HR>

<P>

Perl has a large number of fuNCtions and an even wider range of

additional modules each with its own additional fuNCtions. This

appendix lists all the standard fuNCtions alphabetically for refereNCe.

<P>

Each fuNCtion has been assigned one or more categories to aid

you in finding the fuNCtion that you need. This is a very rough

categorization, as many fuNCtions might overlap in any category

scheme.

<P>

For each fuNCtion, the needed parameters are shown. The parameters

are described in the text where the meaning is not obvious.

<P>

Quite a few of Perl's fuNCtion mirror those available to C programmers

under the UNIX system and are at least moderately complicated

to use. Please look in the UNIX documentation for additional information

if you're interested in the socket, shared memory, or semaphore

fuNCtions.

<H2><A NAME="FuNCtionsbyCategory"><FONT SIZE=5 COLOR=#FF0000>

FuNCtions by Category</FONT></A></H2>

<P>

This section listed Perl's fuNCtions by category.

<UL>

<LI><B>Array:</B> <TT>chomp</TT>,

<TT>join</TT>, <TT>keys</TT>,

<TT>map</TT>, <TT>pop</TT>,

<TT>push</TT>, <TT>reverse</TT>,

<TT>shift</TT>, <TT>sort</TT>,

<TT>splice</TT>, <TT>split</TT>,

<TT>unshift</TT>, <TT>values</TT>

<LI><B>Database:</B> <TT>dbmclose</TT>,

<TT>dbmopen</TT>

<LI><B>Directory:</B> <TT>chdir</TT>,

<TT>closedir</TT>, <TT>mkdir</TT>,

<TT>opendir</TT>, <TT>readdir</TT>,

<TT>rewinddir</TT>, <TT>rmdir</TT>,

<TT>seekdir</TT>, <TT>telldir</TT>

<LI><B>File:</B> <TT>binmode</TT>,

<TT>chdir</TT>, <TT>chmod</TT>,

<TT>chown</TT>, <TT>chroot</TT>,

<TT>close</TT>, <TT>eof</TT>,

<TT>fNCtl</TT>, <TT>fileno</TT>,

<TT>flock</TT>, <TT>getc</TT>,

<TT>glob</TT>, <TT>ioctl</TT>,

<TT>link</TT>, <TT>lstat</TT>,

<TT>open</TT>, <TT>print</TT>,

<TT>printf</TT>, <TT>read</TT>,

<TT>readdir</TT>, <TT>readlink</TT>,

<TT>rename</TT>, <TT>rmdir</TT>,

<TT>seek</TT>, <TT>select</TT>,

<TT>stat</TT>, <TT>symlink</TT>,

<TT>sysopen</TT>, <TT>sysread</TT>,

<TT>syswrite</TT>, <TT>tell</TT>,

<TT>truNCate</TT>, <TT>umask</TT>,

<TT>unlink</TT>, <TT>utime</TT>,

<TT>write</TT>

<LI><B>Group:</B> <TT>endgrent</TT>,

<TT>getgrent</TT>, <TT>getgrgid</TT>,

<TT>getgrname</TT>, <TT>getpgrp</TT>,

<TT>setgrent</TT>, <TT>setpgrp</TT>

<LI><B>Hash:</B> <TT>delete</TT>,

<TT>each</TT>, <TT>exists</TT>,

<TT>keys</TT>, <TT>values</TT>

<LI><B>Host:</B> <TT>endhostent</TT>,

<TT>gethostbyaddr</TT>, <TT>gethostbyname</TT>,

<TT>sethostent</TT>

<LI><B>Input:</B> <TT>getc</TT>, <TT>read</TT>,

<TT>sysread</TT>

<LI><B>Inter-process Communication:</B> <TT>msgctl</TT>,

<TT>msgget</TT>, <TT>msgrcv</TT>,

<TT>msgsnd</TT>, <TT>pipe</TT>,

<TT>semctl</TT>, <TT>semget</TT>,

<TT>semop</TT>, <TT>shmctl</TT>,

<TT>shmget</TT>, <TT>shmread</TT>,

<TT>shmwrite</TT>

<LI><B>Math:</B> <TT>abs</TT>, <TT>atan2</TT>,

<TT>cos</TT>, <TT>exp</TT>,

<TT>hex</TT>, <TT>int</TT>,

<TT>log</TT>, <TT>oct</TT>,

<TT>rand</TT>, <TT>sin</TT>,

<TT>sqrt</TT>, <TT>srand</TT>

<LI><B>Message Queues:</B> <TT>msgctl</TT>,

<TT>msgget</TT>, <TT>msgrcv</TT>,

<TT>msgsnd</TT>

<LI><B>Miscellaneous:</B> <TT>bless</TT>,

<TT>defined</TT>, <TT>do</TT>,

<TT>eval</TT>, <TT>formline</TT>,

<TT>import</TT>, <TT>ref</TT>,

<TT>scalar</TT>, <TT>syscall</TT>,

<TT>tie</TT>, <TT>tied</TT>,

<TT>undef</TT>, <TT>untie</TT>,

<TT>wantarray</TT>

<LI><B>Network:</B> <TT>endnetent</TT>,

<TT>getnetbyaddr</TT>, <TT>getnetbyname</TT>,

<TT>getnetent</TT>, <TT>setnetent</TT>

<LI><B>Output:</B> <TT>die</TT>, <TT>print</TT>,

<TT>printf</TT>, <TT>syswrite</TT>,

<TT>warn</TT>, <TT>write</TT>

<LI><B>Password:</B> <TT>endpwent</TT>,

<TT>getpwent</TT>, <TT>getpwname</TT>,

<TT>getpwuid</TT>, <TT>setpwent</TT>

<LI><B>Process:</B> <TT>alarm</TT>,

<TT>die</TT>, <TT>dump</TT>,

<TT>exec</TT>, <TT>exit</TT>,

<TT>fork</TT>, <TT>getlogin</TT>,

<TT>getpgrp</TT>, <TT>getppid</TT>,

<TT>getpriority</TT>, <TT>kill</TT>,

<TT>setpriority</TT>, <TT>sleep</TT>,

<TT>system</TT>, <TT>times</TT>,

<TT>umask</TT>, <TT>wait</TT>,

<TT>waitpid</TT>

<LI><B>Protocol:</B> <TT>endprotent</TT>,

<TT>getprotobyname</TT>, <TT>getprotobynumber</TT>,

<TT>getprotoent</TT>, <TT>getservbyname</TT>,

<TT>getservbyport</TT>, <TT>getservent</TT>,

<TT>setprotoent</TT>

<LI><B>Regular Expression:</B> <TT>grep</TT>,

<TT>pos</TT>, <TT>quotemeta</TT>,

<TT>reset</TT>, <TT>split</TT>,

<TT>study</TT>

<LI><B>Scope:</B> <TT>caller</TT>,

<TT>local</TT>, <TT>my</TT>

<LI><B>Service:</B> <TT>endservent</TT>,

<TT>getservbyname</TT>, <TT>getservbyport</TT>,

<TT>getservent</TT>, <TT>setservent</TT>

<LI><B>Socket:</B> <TT>accept</TT>,

<TT>bind</TT>, <TT>connect</TT>,

<TT>gethostbyaddr</TT>, <TT>gethostbyname</TT>,

<TT>gethostent</TT>, <TT>getpeername</TT>,

<TT>getservbyname</TT>, <TT>getservbyport</TT>,

<TT>getservent</TT>, <TT>getsockname</TT>,

<TT>getsockopt</TT>, <TT>listen</TT>,

<TT>recv</TT>, <TT>select</TT>,

<TT>send</TT>, <TT>setsockopt</TT>,

<TT>shutdown</TT>, <TT>socket</TT>,

<TT>socketpair</TT>

<LI><B>String:</B> <TT>chop</TT>,

<TT>chr</TT>, <TT>crypt</TT>,

<TT>hex</TT>, <TT>index</TT>,

<TT>join</TT>, <TT>lc</TT>,

<TT>lcfirst</TT>, <TT>length</TT>,

<TT>oct</TT>, <TT>pack</TT>,

<TT>q</TT>, <TT>qq</TT>,

<TT>quotemeta</TT>, <TT>qw</TT>,

<TT>qx</TT>, <TT>reverse</TT>,

<TT>rindex</TT>, <TT>split</TT>,

<TT>sprintf</TT>, <TT>substr</TT>,

<TT>uc</TT>, <TT>ucfirst</TT>,

<TT>unpack</TT>, <TT>vec</TT>

<LI><B>Time:</B> <TT>gmtime</TT>,

<TT>localtime</TT>, <TT>time</TT>

<LI><B>UNIX:</B> <TT>chmod</TT>, <TT>chown</TT>,

<TT>chroot</TT>, <TT>dump</TT>,

<TT>endgrent</TT>, <TT>endhostent</TT>,

<TT>endnetent</TT>, <TT>endprotent</TT>,

<TT>endpwent</TT>, <TT>endservent</TT>,

<TT>fNCtl</TT>, <TT>fork</TT>,

<TT>getgrent</TT>, <TT>getgrgid</TT>,

<TT>getgrname</TT>, <TT>gethostent</TT>,

<TT>getlogin</TT>, <TT>getnetent</TT>,

<TT>getpgrp</TT>, <TT>getppid</TT>,

<TT>getpriority</TT>, <TT>getprotobyname</TT>,

<TT>getprotobynumber</TT>, <TT>getprotoent</TT>,

<TT>getpwent</TT>, <TT>getpwname</TT>,

<TT>getpwuid</TT>, <TT>getservbyname</TT>,

<TT>getservbyport</TT>, <TT>getservent</TT>,

<TT>ioctl</TT>, <TT>link</TT>,

<TT>lstat</TT>, <TT>readlink</TT>,

<TT>select</TT>, <TT>setgrent</TT>,

<TT>sethostent</TT>, <TT>setnetent</TT>,

<TT>setpgrp</TT>, <TT>setpriority</TT>,

<TT>setprotoent</TT>, <TT>setpwent</TT>,

<TT>setservent</TT>, <TT>sleep</TT>,

<TT>syscall</TT>, <TT>times</TT>,

<TT>umask</TT>, <TT>wait</TT>,

<TT>waitpid</TT>

</UL>

<H2><A NAME="FuNCtionsbyName"><FONT SIZE=5 COLOR=#FF0000>

FuNCtions by Name</FONT></A></H2>

<P>

Here is the list of Perl's fuNCtion sorted by name.

<H3><A NAME="absEXPR">

abs([EXPR])</A></H3>

<P>

<B>Category:</B> Math<BR>

<B>Return Value:</B> scalar, the absolute value of <TT>EXPR</TT>

or <TT>$_</TT> if no expression is

specified.<BR>

<B>Definition:</B> Calculates an absolute value. For example,

<TT>abs(-10)</TT> is 10.

<H3><A NAME="acceptNEWSOCKETGENERICSOCKET">

accept (NEWSOCKET, GENERICSOCKET)</A></H3>

<P>

<B>Category:</B> Socket<BR>

<B>Return Value:</B> SCALAR, the packed address of the client

or false if a problem occurred.<BR>

<B>Definition:</B> Accepts a socket connection from clients waiting

for a connection. The <TT>GENERICSOCKET</TT>

parameter must have already been opened using the <TT>socket()</TT>

fuNCtion. You can find more information about <TT>accept()</TT>

in section 2 of the UNIX manual pages.

<H3><A NAME="alarmNUMOFSECONDS">

alarm (NUM_OF_SECONDS)</A></H3>

<P>

<B>Category:</B> Process<BR>

<B>Return Value:</B> SCALAR, the number of seconds remaining before

the previous alarm was due to go off.<BR>

<B>Definition:</B> Sends a SIGALARM to your script after NUM_OF_SECONDS.

A call with NUM_OF_SECONDS equal to zero caNCels the current alarm.

You can find more information about <TT>alarm()</TT>

in section 3 of the UNIX manual pages. It is poss-ible for Perl

to trap such signals and call specific signal handling subroutines.

See <A HREF="ch13.htm" >Chapter 13</A>, &quot;Handling Errors and Signals.&quot;

<BLOCKQUOTE>

<PRE>

alarm(10);

</PRE>

</BLOCKQUOTE>

<H3><A NAME="atanEXPR">

atan2 ([EXPR])</A></H3>

<P>

<B>Category:</B> Math<BR>

<B>Return Value:</B> SCALAR, the arc tangent of <TT>EXPR</TT>

or of <TT>$_</TT> if no expression

is specified.<BR>

<B>Definition:</B>  Calculates an arc tangent.

<BLOCKQUOTE>

<PRE>

$arcTangent = atan2(60,2);

</PRE>

</BLOCKQUOTE>

<H3><A NAME="bindSOCKETNAME">

bind (SOCKET, NAME)</A></H3>

<P>

<B>Category:</B> Socket<BR>

<B>Return Value:</B> SCALAR, the socket handle or false if an

error occurred.<BR>

<B>Definition:</B> Binds a network address to the socket handle.

You can find more information about <TT>bind()</TT>

in section 2 of the UNIX manual pages.

<H3><A NAME="binmodeFILEHANDLE">

binmode (FILEHANDLE)</A></H3>

<P>

<B>Category:</B> File<BR>

<B>Return Value:</B> SCALAR, true if successful or undefined if

not.<BR>

<B>Definition:</B> On systems which distinguish between text and

binary files (like Windows 95 and Windows NT) this fuNCtion forces

binary mode treatment of <TT>FILEHANDLE</TT>.

In systems which do make the distiNCtion, text files have the

end of line characters-carriage return (<TT>'\r'</TT>)

and linefeed(<TT>'\n'</TT>)-automatically

translated into the UNIX end-of-line character (<TT>'\n'</TT>)

when reading from the file and when writing to the file. Binary

mode files do not have this automatic transformation. See &quot;Example:

Binary Files&quot; in <A HREF="ch9.htm" >Chapter 9</A> &quot;Using Files,&quot; for

more information.

<BLOCKQUOTE>

<PRE>

open(FILE, &quot;file.dat&quot;);

binmode(FILE);

</PRE>

</BLOCKQUOTE>

<H3><A NAME="blessREFERENCECLASSNAME">

bless (REFERENCE, [CLASSNAME])</A></H3>

<P>

<B>Category:</B> Object<BR>

<B>Return Value:</B> SCALAR, a refereNCe to the blessed object.

<BR>

<B>Definition:</B> Changes the type of the refereNCed variable

to <TT>CLASSNAME</TT>. It is used

to assign a class name to the refereNCed variable, thus changing

the string returned by the <TT>ref()</TT>

fuNCtion. If <TT>CLASSNAME</TT> is

not specified, the name of the current package is used. See Chapter

8, &quot;RefereNCes,&quot; for more information.

<BLOCKQUOTE>

<PRE>

$temp = { }

bless $temp, 'ATMPCLASS';

print(&quot;bless() \$temp is now has type &quot;, ref($temp), &quot;\n&quot;);

<BR>



</PRE>

</BLOCKQUOTE>

<p>

<CENTER>

<TABLE BORDERCOLOR=#000000 BORDER=1 WIDTH=80%>

<TR><TD><B>Tip</B></TD></TR>

<TR><TD>

<BLOCKQUOTE>

Always specify the <TT>CLASSNAME</TT> parameter if the blessing fuNCtion might be inherited.

</BLOCKQUOTE>



</TD></TR>

</TABLE>

</CENTER>

<P>

<H3><A NAME="callerEXPR">

caller ([EXPR])</A></H3>

<P>

<B>Category:</B> Scope<BR>

<B>Return Value:</B> in Scalar Context: SCALAR, true if the current

code has been called as a subroutine (this iNCludes code which

is iNCluded using a <TT>require()</TT>

or an <TT>eval() call)</TT>. Otherwise,

false.<BR>

<B>Return Value in Array Context:</B> ARRAY, contains details

of the calling context comprising the package name, file name,

and line of the call.<BR>

<B>Definition:</B> This fuNCtion is used to test the current scope

of a subroutine call.

<BLOCKQUOTE>

<PRE>

sub testcaller {

    ($package, $file, $line) = caller;

print(&quot;caller() Package=$package File=$file Line=$line\n&quot;);

}

testcaller();

</PRE>

</BLOCKQUOTE>

<H3><A NAME="chdirDIRNAME">

chdir ([DIRNAME])</A></H3>

<P>

<B>Category:</B> Directory<BR>

<B>Return Value:</B> SCALAR, true if successful, false otherwise.

<BR>

<B>Definition:</B> Changes the current directory to the directory

specified. If no argument is given changes to the home directory

of the current user.

<BLOCKQUOTE>

<PRE>

chdir(&quot;/&quot;) ? print(&quot;It worked.\n&quot;) : print(&quot;It didn't work.\n&quot;);

</PRE>

</BLOCKQUOTE>

<H3><A NAME="chmodMODELIST">

chmod (MODE, LIST)</A></H3>

<P>

<B>Category:</B> File, UNIX<BR>

<B>Return Value:</B> SCALAR, the number of files changed.<BR>

<B>Definition:</B> <TT>MODE</TT> is

an octal number representing file permissions which are applied

to all the files in <TT>LIST</TT>.

<BLOCKQUOTE>

<PRE>

chmod(0744, &quot;test1.txt&quot;, &quot;test2.txt&quot;);

</PRE>

</BLOCKQUOTE>

<H3><A NAME="chompSTRINGLIST">

chomp ([STRING | LIST])</A></H3>

<P>

<B>Category:</B> Array, String<BR>

<B>Return Value:</B> SCALAR, the number of characters removed.

<BR>

<B>Definition:</B> This is a safer alternative than the <TT>chop()</TT>

fuNCtion for removing characters at the end of strings. <TT>Chomp()</TT>

only removes characters that correspond to the value of <TT>$/</TT>

(the input line separator). It can be given a list of strings

upon which to perform this operation. When given no arguments

the chomp operation is performed on <TT>$_</TT>.

<BLOCKQUOTE>

<PRE>

$temp = &quot;AAAAA!\n&quot;;

print(&quot;chomp(\$temp) returned &quot;, chomp($temp), &quot;.\n&quot;);

</PRE>

</BLOCKQUOTE>

<H3><A NAME="chopSTRINGLIST">

chop ([STRING | LIST])</A></H3>

<P>

<B>Category:</B> Array, String<BR>

<B>Return Value:</B> SCALAR, the last character that was removed.

<BR>

<B>Definition:</B> This fuNCtion removes the last character of

<TT>STRING</TT> or the last character

of each element in <TT>LIST</TT>.

<BLOCKQUOTE>

<PRE>

$tmp = &quot;1234&quot;;

print(&quot;chop(\$tmp) returned &quot;, chop($tmp), &quot;\n&quot;);

<BR>



</PRE>

</BLOCKQUOTE>

<p>

<CENTER>

<TABLE BORDERCOLOR=#000000 BORDER=1 WIDTH=80%>

<TR><TD><B>Tip</B></TD></TR>

<TR><TD>

<BLOCKQUOTE>

Use <TT>chomp()</TT> (with <TT>$/</TT> set to &quot;\n&quot;) rather than <TT>chop()</TT> if you are not sure that the string has a trailing newline.