???? ??????(δ????)

??????	eval
??????	eval(string)
???	??string????Perl?????С? ?????к???????$@??????????д???$@????????????
????	$print = "print (\"hello,world\\n\");"; eval ($print);
??????	hello, world

??????	system
??????	system(list)
???	list?е??????????????????????????? system?????????????г?????????????????????????????????λ??????????
????	@proglist = ("echo", "hello,world!"); system(@proglist);
??????	hello, world!

??????	fork
??????	procid = fork();
???	?????????????????--????????????--?????С???????????????????????????????????????ID???
????	$retval = fork(); if ($retval == 0) {   # this is the child process   exit; # this terminates the child process } else {   # this is the parent process }
??????	??

??????	pipe
??????	pipe (infile, outfile);
???	??fork????????????????????????????????outfile???????????????????infile???????????????裺 1??????pipe 2????fork??????????????????? 3???????????infile??????????outfile
????	pipe (INPUT, OUTPUT); $retval = fork(); if ($retval != 0) {   # this is the parent process   close (INPUT);   print ("Enter a line of input:\n");   $line = <STDIN>;   print OUTPUT ($line); } else {   # this is the child process   close (OUTPUT);   $line = <INPUT>;   print ($line);   exit (0); }
??????	$ program Enter a line of input: Here is a test line Here is a test line $

??????	exec
??????	exec (list);
???	??system???????????????????????????????????fork???????fork???????????????????exec????????????
????
??????

??????	syscall
??????	syscall (list);
???	????????????list??????????????????????????????? ?????????????????????C????????(type int)?????????????????????UNIX???????Perl????? ???syscall??????????syscall.pl?????? require ("syscall.ph");
????
??????

??????	sleep
??????	sleep (time);
???	???????????????time???????????????????????????????
????	sleep (5);
??????	??

??????	wait
??????	procid = wait();
???	?????????У?????????????? ??????????????????????ID??????????????????-1??
????
??????

??????	waitpid
??????	waitpid (procid, waitflag);
???	?????????У???????????????????procid?????????ID
????	$procid = fork(); if ($procid == 0) {   # this is the child process   print ("this line is printed first\n");   exit(0); } else {   # this is the parent process   waitpid ($procid, 0);   print ("this line is printed last\n"); }
??????	$ program this line is printed first this line is printed last $

??????	caller
??????	subinfo = caller();
???	??????????????????к??????Perl Debugger?? ?????????????б?? 1???????????? 2????????????? 3??????????к?
????
??????

??????	chroot
??????	chroot (dir);
???	???????????????chroot??????
????
??????

??????	local
??????	local($variable);
???	??????(????????Χ????伯??)?ж?????????????????????????????????????????????????????? ???????????????????????????????????μ?????????
????
??????

??????	times
??????	timelist = times
???	????ó??????????????????????? ??????????????????б?? 1???????????????? 2??????????????? 3????????????????? 4????????????????
????
??????

??????	sin
??????	retval = sin (value);
???	????????????

??????	cos
??????	retval = cos (value);
???	????????????

??????	atan2
??????	retval = atan2 (value1, value2);
???	????????value1????value2?????arctan?????λ????????Χ??-PI~PI??
??????? ????????????????	sub degrees_to_radians {   local ($degrees) = @_;   local ($radians);11:   $radians = atan2(1,1) * $degrees / 45; }

??????	sqrt
??????	retval = sqrt (value);
???	???????????value????????

??????	exp
??????	retval = exp (value);
???	????e??value?η???

??????	log
??????	retval = log (value);
???	??e?????????????

??????	abs
??????	retval = abs (value);
???	???????????(Perl 4?????)

??????	rand
??????	retval = rand (num);
???	???????????????0??????num???????????????

??????	srand
??????	srand (value);
???	???????????????????????ε???rand?????????

??????	index
??????	position = index (string, substring, position);
???	???????substring???????string?е?λ????????????????-1??????position???????????????????????????????????λ???????

??????	rindex
??????	position = rindex (string, substring, position);
???	??index??????????????????

??????	length
??????	num = length (string);
???	?????????????????????????????????

??????	pos
??????	offset = pos(string);
???	????????????????λ?á?

??????	substr
??????	substr (expr, skipchars, length)
???	???????????????????????????expr?е??????????skipchars??????????????λ??skipchars???????????????????λ???0????????????length???????????????ζ?????μ????????? ?????????????????????expr?????????????????????????в?????????????????滻??

??????	study
??????	study (scalar);
???	??????????????????????????????????????????????á?

??????	lc uc
??????	retval = lc(string); retval = uc(string);
???	???????????????С/??д?????

??????	lcfirst ucfirst
??????	retval = lcfirst(string); retval = ucfirst(string);
???	???????????????С/??д??

??????	quotameta
??????	newstring = quotemeta(oldstring);
???	??????????????????б??(\)?? ??? ?? $string = quotemeta($string); ??Ч???$string =~ s/(\W)/\\$1/g; ???????????????У?????????????????????????????????

??????	join
??????	join (joinstr, list);
???	????????б?(????)??????????????????????????б????????joinstr??

??????	sprintf
??????	sprintf (string, fields);
???	??printf?????????????????????????????????????????????
????	$num = 26; $outstr = sprintf("%d = %x hexadecimal or %o octal\n",$num, $num, $num); print ($outstr);
??????	26 = 1a hexadecimal or 32 octal

??????	chop
??????	$lastchar = chop (var);
???	var????????????飬??var????????????????????????????$lastchar????var?????/?б???????????????????????????????????????????????????$lastchar??

??????	chomp
??????	result = chomp(var);
???	????????????????б????????????????????????????$/??????з???????????????????????????????????????

??????	crypt
??????	result = crypt (original, salt);
???	??DES?????????????original????????????????salt????????????????????????θ??DES?????????????????????????????

??????	hex
??????	decnum = hex (hexnum);
???	???????????(????????)?????????????

??????	int
??????	intnum = int (floatnum);
???	???????????С??????????????????

??????	oct
??????	decnum = oct (octnum);
???	?????????(????????)???????????("0x.."???)?????????????

??????	ord
??????	asciival = ord (char);
???	????????????ASCII?????PASCAL??????????????

??????	chr
??????	$char = chr (asciival);
???	????ASCII?????????????PASCAL??????????????

??????	pack
??????	formatstr = pack(packformat, list);
???	??????б?????????????????????????C????????????????????????????????????С?????packformat????????????????????б????????????????????????????????tab????????pack??????   ??????a??A??@???????????????ο???????????????磺    $twoints = pack ("i2", 103, 241);   ???????????????е????????*????磺    $manyints = pack ("i*", 14, 26, 11, 83);   ????a??A???????????????????????????????????????????￡?    $strings = pack ("a6" x 2, "test1", "test2");   ???@???????????????????????????????????????????????????????????????????(null)?????磺    $output = pack ("a @6 a", "test", "test2");   pack??????????????????????C?????????????????C???????????????????(null)??β???????????????????????????    $Cstring = pack ("ax", $mystring);   ?±????Щ????????C????????????????? ???   ???C???????? C char d double f float i int I unsigned int (or unsigned) l long L unsigned long s short S unsigned short   ??????????????±??

??????	????
a	??????(null)??????????
A	????????????
b	λ??????λ???
B	λ??????λ???
c	??????????????-128~127??
C	?????????????8λ??
d	??????????
f	???????????
h	???????????????λ???
H	???????????????λ???
i	??????????
I	?????????
l	???????????
L	??????????
n	???????????
N	??????????
p	????????
s	???????????
S	??????????
u	?????uuencode???
v	VAX???????
V	VAX??????
x	????????
X	??????????
@	??????(null)???

??????	unpack
??????	@list = unpack (packformat, formatstr);
???	unpack??pack??????????????????????????????Perl??????б???????????pack???????????????????????У?A?????????????????????Perl??????????β?????п?????????x????????????@??????Щ?????????λ?????@4?????4?????????濴???@??X??????????    $longrightint = unpack ("@* X4 L", $packstring);   ????佫??????????????????????????????????濴?????uuencode????????????? 1 : #!/usr/local/bin/perl 2 : 3 : open (CODEDFILE, "/u/janedoe/codefile") || 4 : die ("Can't open input file"); 5 : open (OUTFILE, ">outfile") || 6 : die ("Can't open output file"); 7 : while ($line = <CODEDFILE>) { 8 : $decoded = unpack("u", $line); 9 : print OUTFILE ($decoded); 10: } 11: close (OUTFILE); 12: close (CODEDFILE);   ????pack??unpack????uuencode??????????????????UNIX?е?uuencode??uudecode??????????????????????к???У????????uudecode????pack?????????????????н?????????????к????????????UNIX??uuencode????????

??????	vec
??????	retval = vec (vector, index, bits);
???	??????壬vec?????(vector)???????????????vector??????????(?)???????麬????????λ???????????????????????ε???÷????????????????????????????д??????index?????????±?????????????????飬0?????飬???????????????????????????????????????????????????bits???????е?λ?????????1,2,4,8,16??32??
????	1 : #!/usr/local/bin/perl 2 : 3 : $vector = pack ("B*", "11010011"); 4 : $val1 = vec ($vector, 0, 4); 5 : $val2 = vec ($vector, 1, 4); 6 : print ("high-to-low order values: $val1 and $val2\n"); 7 : $vector = pack ("b*", "11010011"); 8 : $val1 = vec ($vector, 0, 4); 9 : $val2 = vec ($vector, 1, 4); 10: print ("low-to-high order values: $val1 and $val2\n");
???	high-to-low order values: 3 and 13 low-to-high order values: 11 and 12

??????	defined
??????	retval = defined (expr);
???	?ж???????????????????????????????????????expr???????????????????????????? ???????壬?????棬????????

??????	undef
??????	retval = undef (expr);
???	?????????????????????????????????壬?????????????????δ????????????????Ч??

??????	grep
??????	@foundlist = grep (pattern, @searchlist);
???	???????UNIX????????????grep???????б??г?????????????????????pattern???????????????????????????б??
????	@list = ("This", "is", "a", "test"); @foundlist = grep(/^[tT]/, @list);
???	@foundlist = ("This", "test");

??????	splice
??????	@retval = splice (@array, slipelements, length, @newlist);
???	?????????????б?????飩?м??????????????б???滻???б??????skipelements????????????????????length????滻?????????newlist?????????????б????newlist????????length???????????????????????????????????????length=0????????????б??в????????????????   splice (@array, -1, 0, "Hello"); ?????????β???????????newlist????????????????б??????????length????????skipelements?????????????????????????????????splice (@array, -1);????????￡?????????????????б??

??????	shift
??????	element = shift (@arrayvar);
???	????????????????????????????????????????????????????@ARGV???в?????

??????	unshift
??????	count = unshift (@arrayver, elements);
???	??????shift??????????arrayvar???????????????????????????(?б?)???????????splice (@array, 0, 0, elements);

??????	push
??????	push (@arrayvar, elements);
???	???????β????????????????????slice (@array, @array, 0, elements);

??????	pop
??????	element = pop (@arrayvar);
???	??push???????????б??????????????????????????????б??????????δ???????(?????)??

??????	split
??????	@list = split (pattern, string, maxlength);
???	???????????????????б?????????pattern?????????????????pattern???????????????С?maxlength???????????????????ó????????��

??????	sort
??????	@sorted = sort (@list);
???	???????????б?????

??????	reverse
??????	@reversed = reverse (@list);
???	???????????б?????

??????	map
??????	@resultlist = map (expr, @list);
???	???????Perl5?ж??壬??????б??е??????????????expr?????????????????????????????????????????expr?У???????$_???????????
????	1??@list = (100, 200, 300);    @results = map ($_+1, @list); 2??@results = map (&mysub($_), @list);
???	1??(101, 201, 301) 2????

??????	wantarray
??????	result = wantarray();
???	Perl?У??Щ???ú????????????????????????????????????????chop??????????????????????????????????????????????????б????????????????????(??)??????????(??)??
????	1 : #!/usr/local/bin/perl 2 : 3 : @array = &mysub(); 4 : $scalar = &mysub(); 5 : 6 : sub mysub { 7 : if (wantarray()) { 8 : print ("true\n"); 9 : } else { 10: print ("false\n"); 11: } 12: }
???	$program true false $

??????	keys
??????	@list = keys (%assoc_array);
???	?????????????????±??б??

??????	values
??????	@list = values (%assoc_array);
???	??????????????????б??

??????	each
??????	@pair = each (%assoc_array);
???	?????????????б?--?????????±???????????????????????????????????????б??

??????	delete
??????	element = delete (assoc_array_item);
???	????????????е??????????????????????
????	%array = ("foo", 26, "bar", 17"); $retval = delete ($array{"foo"});
???	$retval = 26;

??????	exists
??????	result = exists (element);
???	??Perl5?ж??壬?ж???????????????????????????????????(??)???????????(??)??
????	$result = exists ($myarray{$mykey});

????? ??