smarty/docs/en/designers/language-builtin-functions/language-function-if.xml

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<sect1 id="language.function.if">
 <title>{if},{elseif},{else}</title>
 <para>
  <emphasis>{if}</emphasis> statements in Smarty have much the same flexibility as PHP
  <ulink url="&url.php-manual;if"><command>if</command></ulink>
  statements, with a few added features for the template engine.
  Every <emphasis>{if}</emphasis> must be paired with an
  <emphasis>{/if}</emphasis>. <emphasis>{else}</emphasis> and
  <emphasis>{elseif}</emphasis> are also permitted. All PHP conditionals
  and functions 
  are recognized, such as <emphasis>||</emphasis>, <emphasis>or</emphasis>,
  <emphasis>&amp;&amp;</emphasis>, <emphasis>and</emphasis>, 
  <emphasis>is_array()</emphasis>, etc.
 </para>

 <para>
  The following is a list of recognized qualifiers, which must be
  separated from surrounding elements by spaces. Note that items listed
  in [brackets] are optional. PHP equivalents are shown where applicable.
 </para>

 <informaltable frame="all">
  <tgroup cols="4">
   <colspec colname="qualifier" align="center" />
   <colspec colname="alternates" align="center" />
   <colspec colname="meaning" />
   <colspec colname="example" />
   <colspec colname="php" />
   <thead>
    <row>
     <entry>Qualifier</entry>
     <entry>Alternates</entry>
     <entry>Syntax Example</entry>
     <entry>Meaning</entry>
     <entry>PHP Equivalent</entry>
    </row>
   </thead>
   <tbody>
    <row>
     <entry>==</entry>
     <entry>eq</entry>
     <entry>$a eq $b</entry>
     <entry>equals</entry>
     <entry>==</entry>
    </row>
    <row>
     <entry>!=</entry>
     <entry>ne, neq</entry>
     <entry>$a neq $b</entry>
     <entry>not equals</entry>
     <entry>!=</entry>
    </row>
    <row>
     <entry>&gt;</entry>
     <entry>gt</entry>
     <entry>$a gt $b</entry>
     <entry>greater than</entry>
     <entry>&gt;</entry>
    </row>
    <row>
     <entry>&lt;</entry>
     <entry>lt</entry>
     <entry>$a lt $b</entry>
     <entry>less than</entry>
     <entry>&lt;</entry>
    </row>
    <row>
     <entry>&gt;=</entry>
     <entry>gte, ge</entry>
     <entry>$a ge $b</entry>
     <entry>greater than or equal</entry>
     <entry>&gt;=</entry>
    </row>
    <row>
     <entry>&lt;=</entry>
     <entry>lte, le</entry>
     <entry>$a le $b</entry>
     <entry>less than or equal</entry>
     <entry>&lt;=</entry>
    </row>
    <row>
     <entry>===</entry>
     <entry></entry>
     <entry>$a === 0</entry>
     <entry>check for identity</entry>
     <entry>===</entry>
    </row>
    <row>
     <entry>!</entry>
     <entry>not</entry>
     <entry>not $a</entry>
     <entry>negation (unary)</entry>
     <entry>!</entry>
    </row>
    <row>
     <entry>%</entry>
     <entry>mod</entry>
     <entry>$a mod $b</entry>
     <entry>modulous</entry>
     <entry>%</entry>
    </row>
    <row>
     <entry>is [not] div by</entry>
     <entry></entry>
     <entry>$a is not div by 4</entry>
     <entry>divisible by</entry>
     <entry>$a % $b == 0</entry>
    </row>
    <row>
     <entry>is [not] even</entry>
     <entry></entry>
     <entry>$a is not even</entry>
     <entry>[not] an even number (unary)</entry>
     <entry>$a % 2 == 0</entry>
    </row>
    <row>
     <entry>is [not] even by</entry>
     <entry></entry>
     <entry>$a is not even by $b</entry>
     <entry>grouping level [not] even</entry>
     <entry>($a / $b) % 2 == 0</entry>
    </row>
    <row>
     <entry>is [not] odd</entry>
     <entry></entry>
     <entry>$a is not odd</entry>
     <entry>[not] an odd number (unary)</entry>
     <entry>$a % 2 != 0</entry>
    </row>
    <row>
     <entry>is [not] odd by</entry>
     <entry></entry>
     <entry>$a is not odd by $b</entry>
     <entry>[not] an odd grouping</entry>
     <entry>($a / $b) % 2 != 0</entry>
    </row>
   </tbody>
  </tgroup>
 </informaltable>
 <example>
  <title>{if} statements</title>
  <programlisting>
<![CDATA[
{if $name eq "Fred"}
    Welcome Sir.
{elseif $name eq "Wilma"}
    Welcome Ma'am.
{else}
    Welcome, whatever you are.
{/if}

{* an example with "or" logic *}
{if $name eq "Fred" or $name eq "Wilma"}
   ...
{/if}

{* same as above *}
{if $name == "Fred" || $name == "Wilma"}
   ...
{/if}

{*
  the following syntax will NOT work, conditional qualifiers
  must be separated from surrounding elements by spaces
*}
{if $name=="Fred" || $name=="Wilma"}
   ...
{/if}


{* parenthesis are allowed *}
{if ( $amount < 0 or $amount > 1000 ) and $volume >= #minVolAmt#}
   ...
{/if}

{* you can also embed php function calls *}
{if count($var) gt 0}
   ...
{/if}

{* test if values are even or odd *}
{if $var is even}
   ...
{/if}
{if $var is odd}
   ...
{/if}
{if $var is not odd}
   ...
{/if}

{* test if var is divisible by 4 *}
{if $var is div by 4}
   ...
{/if}

{*
  test if var is even, grouped by two. i.e.,
  0=even, 1=even, 2=odd, 3=odd, 4=even, 5=even, etc.
*}
{if $var is even by 2}
   ...
{/if}

{* 0=even, 1=even, 2=even, 3=odd, 4=odd, 5=odd, etc. *}
{if $var is even by 3}
   ...
{/if}

{* ------- if with php functions ------- *}
{* check for array. *}
{if is_array($foo) }
   .....
{/if}

{* check for array. *}
{if isset($foo) }
   .....
{/if}

]]>
  </programlisting>
 </example>
</sect1>
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