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><TT
CLASS="literal"
>switch</TT
></H1
><P
>&#13;    The <TT
CLASS="literal"
>switch</TT
> statement is similar to a series of
    IF statements on the same expression.  In many occasions, you may
    want to compare the same variable (or expression) with many
    different values, and execute a different piece of code depending
    on which value it equals to.  This is exactly what the
    <TT
CLASS="literal"
>switch</TT
> statement is for.
   </P
><P
>&#13;    The following two examples are two different ways to write the
    same thing, one using a series of <TT
CLASS="literal"
>if</TT
>
    statements, and the other using the <TT
CLASS="literal"
>switch</TT
>
    statement:
    <DIV
CLASS="informalexample"
><A
NAME="AEN5025"
></A
><P
></P
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><PRE
CLASS="php"
>if ($i == 0) {
    print "i equals 0";
}
if ($i == 1) {
    print "i equals 1";
}
if ($i == 2) {
    print "i equals 2";
}

switch ($i) {
    case 0:
        print "i equals 0";
        break;
    case 1:
        print "i equals 1";
        break;
    case 2:
        print "i equals 2";
        break;
}</PRE
></TD
></TR
></TABLE
><P
></P
></DIV
>
   </P
><P
>&#13;    It is important to understand how the <TT
CLASS="literal"
>switch</TT
>
    statement is executed in order to avoid mistakes.  The
    <TT
CLASS="literal"
>switch</TT
> statement executes line by line
    (actually, statement by statement).  In the beginning, no code is
    executed.  Only when a <TT
CLASS="literal"
>case</TT
> statement is found
    with a value that matches the value of the
    <TT
CLASS="literal"
>switch</TT
> expression does PHP begin to execute the
    statements.  PHP continues to execute the statements until the end
    of the <TT
CLASS="literal"
>switch</TT
> block, or the first time it sees
    a <TT
CLASS="literal"
>break</TT
> statement.  If you don't write a
    <TT
CLASS="literal"
>break</TT
> statement at the end of a case's
    statement list, PHP will go on executing the statements of the
    following case.  For example:
    <DIV
CLASS="informalexample"
><A
NAME="AEN5035"
></A
><P
></P
><TABLE
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><TD
><PRE
CLASS="php"
>switch ($i) {
    case 0:
        print "i equals 0";
    case 1:
        print "i equals 1";
    case 2:
        print "i equals 2";
}</PRE
></TD
></TR
></TABLE
><P
></P
></DIV
>
   </P
><P
>&#13;    Here, if $i is equal to 0, PHP would execute all of the print
    statements!  If $i is equal to 1, PHP would execute the last two
    print statements. You would get the expected behavior ('i equals 2' 
    would be displayed) only if $i is equal to 2.  Thus,
    it is important not to forget <TT
CLASS="literal"
>break</TT
> statements
    (even though you may want to avoid supplying them on purpose under
    certain circumstances).
   </P
><P
>&#13;    In a <TT
CLASS="literal"
>switch</TT
> statement, the condition is
    evaluated only once and the result is compared to each
    <TT
CLASS="literal"
>case</TT
> statement. In an <TT
CLASS="literal"
>elseif</TT
>
    statement, the condition is evaluated again. If your condition is
    more complicated than a simple compare and/or is in a tight loop,
    a <TT
CLASS="literal"
>switch</TT
> may be faster.
   </P
><P
>&#13;    The statement list for a case can also be empty, which simply
    passes control into the statement list for the next case.
    <DIV
CLASS="informalexample"
><A
NAME="AEN5045"
></A
><P
></P
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><PRE
CLASS="php"
>switch ($i) {
    case 0:
    case 1:
    case 2:
        print "i is less than 3 but not negative";
        break;
    case 3:
        print "i is 3";
}</PRE
></TD
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><P
></P
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>
   </P
><P
>&#13;    A special case is the default case.  This case matches anything
    that wasn't matched by the other cases, and should be the last
    <TT
CLASS="literal"
>case</TT
> statement.  For example:
    <DIV
CLASS="informalexample"
><A
NAME="AEN5049"
></A
><P
></P
><TABLE
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><TD
><PRE
CLASS="php"
>switch ($i) {
    case 0:
        print "i equals 0";
        break;
    case 1:
        print "i equals 1";
        break;
    case 2:
        print "i equals 2";
        break;
    default:
        print "i is not equal to 0, 1 or 2";
}</PRE
></TD
></TR
></TABLE
><P
></P
></DIV
>
   </P
><P
>&#13;    The <TT
CLASS="literal"
>case</TT
> expression may be any expression that
    evaluates to a simple type, that is, integer or floating-point
    numbers and strings.  Arrays or objects cannot be used here unless
    they are dereferenced to a simple type.
   </P
><P
>&#13;    The alternative syntax for control structures is supported with
    switches. For more information, see <A
HREF="control-structures.alternative-syntax.html"
>Alternative syntax
    for control structures</A
> .
    <DIV
CLASS="informalexample"
><A
NAME="AEN5055"
></A
><P
></P
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><PRE
CLASS="php"
>switch ($i):
    case 0:
        print "i equals 0";
        break;
    case 1:
        print "i equals 1";
        break;
    case 2:
        print "i equals 2";
        break;
    default:
        print "i is not equal to 0, 1 or 2";
endswitch;</PRE
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