Smarty 中的 if 语句和 php 中的 if 语句一样灵活易用，并增加了几个特性以适宜模板引擎. if 必须于 /if 成对出现. 可以使用 else 和 elseif 子句. 可以使用以下条件修饰词：eq、ne、neq、gt、lt、lte、le、gte、ge、is even、is odd、is not even、is not odd、not、mod、div by、even by、odd by、==、!=、>、<、<=、>=. 使用这些修饰词时必须和变量或常量用空格格开.
if 语句实例:
{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}