<?xml version="1.0" encoding="big5"?>
 <chapter id="language.expressions">
   <title>F</title>

   <simpara>
   FO PHP {̮ڥզC  PHP s{AXGҦAgoUӪOyOFC γ²B̺TylӴyzFNOG "󦳭ȪF"C 
</simpara>

   <simpara>
̰򥻪FO`ƩMܼơCAJ "$a = 5"A A '5'  $aC '5'A MNƭ 5A ӻkO '5' O@ӪFA ȬO 5C(bҤA '5' O@ӾƧκA`).
</simpara>

   <simpara>
    oӫާ@A $a Ȥ]ӬO 5A pAAg $b = $aAXGөMg $b = 5 O@˪C ӻkA $a ]@ӪFA FȦPˬO 5C pGS򪺸ܡA oXGNOoӡC
</simpara>

   <para>
FiHΨƨӧ@ܽdC pHUҤlA 
    <informalexample>
     <programlisting>
function foo () {
    return 5;
}
     </programlisting>
    </informalexample></para>

   <simpara>
pAΦ@w{ (p_Ьݦƪ`)A A|PN$c = foo() M $c = 5 oyO@˪C ƹWOoˡC Ƥ]O@تFA ̩ҪFȴNOƪB⵲G(Ǧ^)C ] foo() Ǧ^ 5A ҥHF 'foo()' ȴNO 5C M@ӻƤ|Ǧ^@ӱ`ƦӬOn@ǹB⪺C 

</simpara>

   <simpara>
   MA Ȥ@wOơC PHP iHAΤTؤPΪ¶qȡA OOơBBIơByC(¶qȴNOApqȡAD¶qȪҤlڶqA}C)Ct~ PHP ]䴩}CMD¶qȡC qƶǦ^ȪκAMܼƪȪκAiHOWz@حȡC

</simpara>

   <simpara>
    ثeA  PHP/FI 2 H|ıo򤣤@ˡC MӡA PHP Fi@BoA ܦMܦhO{y@ˡC PHP OHF¦s{yA o˻O]XGҦ PHP ylOѪFզC RWιLҤl '$a = 5'Aܩ㪺bާ@ⶵȡA @O '5'A t@O $a ȡA |Q '5' ҨNC L٦t@ӭȦsbANOFҪFȡC bҤFȴNONȡA ]NO '5'E Ϊɭԧڭ̥iH '$a=5' ݦOӶǦ^ '5' oӭȪFC ѦA pGAg '$b = ($a = 5)' NPg '$a = 5; $b = 5;' (Nyy)C Ai@BA ]FOqkVӰB⪺A ҥHN²檺g '$b = $a = 5'A פ]O@˪C 
</simpara>

   <simpara>
    HF򥻪ާ@٦t~@ثܦnܨҡC NOemΫmWȩMlȾާ@C ϥ PHP/FI 2 M\hLy{jwݺDF ܼ++ M ܼ-- FyC oǫKOWȩMlȹBšC b PHP/FI 2 ɭԡA '$a++' äN (äO@ӪF)A ]򥻤WAΥӰOơC F PHPA oǥyܦFF (N C @)C t~M C ۦPOA ؼWȺšG emMmC س|ܼƼW[ 1A ObFҪFȡC emOg '++$variable'A Ǧ^OWȫ᪺ȡF (PHP bŪFȤeܼƭȥ[ 1A ]sem) mFg '$variable++' Ǧ^ܼ٨SW[ 1 e (PHP ŪFȤ~ܼƼW)C
</simpara>

   <simpara>
O@ط`FC oFB⵲GO 1  0A ON޿ u M C PHP  &gt; (j)F &gt;= (jε)F == ()F != ()F &lt; (p)F &lt;= (pε)C oFq`ΦbyA pif yyC
</simpara>

   <simpara>
    ̫@ӥܽdڭ̷|@PɰMB⪺FC AwDpGQ $a W[ 1A iH '$a++'  '++$a'C OpGAOQ $a W[h@ǡA p '3' ӫ˰@H MiHsg 3 '$a++'A LoܤnݡC kO '$a=$a+3;'G '$a + 3' FO $a A[W 3A oG|^ܼ $a A ӹB⧹ $a e|W[F 3C  PHP M\hLyP˥iH⦹ާ@gt@Ӹ²檺yANӳoإyki|y]zѡC  $a ȼW[ 3 ig '$a += 3'. NNF $a ȮXӡA W[ 3A As^ $a CFuMդ~A oy_Ӥ]֡C oyFǦ^ȩMQ regular expr ɤ@ˡA OFB⪺G '$a+3'C @ӻݭnӹB⤸BųiΦyyyA Ҧp '$a -= 5' ( $a  5), '$b *= 7' ( $b H 7) C
</simpara>

   <para>
t~@جݰ_ӤǦObL{y]|Ψ쪺F: (ternary conditional operator TB⦡) 

    <informalexample><programlisting>
$first ? $second : $third
</programlisting></informalexample>

    Ĥ@ӪF߮ɡA ĤGӪF|QӹB⵲G|ӪFȡC Ĥ@ӪF߮ɡA ĤTӤG|ӪFȡC 
</para>

   <para>
    HUܽd|AnaxemMmWȹBũMFB: 

    <informalexample>
     <programlisting>
function double($i) {
    return $i*2;
}
$b = $a = 5;        /* assign the value five into the variable $a and $b */
$c = $a++;          /* post-increment, assign original value of $a 
                       (5) to $c */
$e = $d = ++$b;     /* pre-increment, assign the incremented value of 
                       $b (6) to $d and $e */

/* at this point, both $d and $e are equal to 6 */

$f = double($d++);  /* assign twice the value of $d <emphasis>before</emphasis> 
                       the increment, 2*6 = 12 to $f */
$g = double(++$e);  /* assign twice the value of $e <emphasis>after</emphasis>
                       the increment, 2*7 = 14 to $g */
$h = $g += 10;      /* first, $g is incremented by 10 and ends with the 
                       value of 24. the value of the assignment (24) is 
                       then assigned into $h, and $h ends with the value 
                       of 24 as well. */
</programlisting></informalexample></para>

   <simpara>
    b}lɧڭ̻|yy statment C FiHOyyA ëDFNOyyC bWҤA yyΦO 'expr' ';' A NO@F[WC p '$b=$a=5;'A $a=5 O@ӦXkFO@yyyC  '$b=$a=5;' ˬO@yXkyyC 
</simpara>

   <simpara>
    ̫Ȫ@OF޿ȡC\hpUA רOyMjyءA FȨäOIϦӸӪFO_ ( &true; ٬O &false;)C (PHP èSSOw޿ܼC) FuȪpkM perl thC 󤣵 0 ƦrNuA 0 hNC ߭tƦ]] 0 A ҥH]NuI ŪyΤy "0" OA ҦLyOuC ܩ󹳰}CMo˪D¶qȡA pGGOŪ}ChNuA ϤhOC 
</simpara>

   <simpara>
    PHP ѤFӥB\jjFC USiҦiΪFykβξzA WܽdiADyykC bUA ڭ̷| expr ӥNXkFC
</simpara>

  </chapter>
 
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