eq相等，
ne、neq不相等，
gt大于，
lt小于，
gte、ge大于等于，
lte、le 小于等于，
not非， mod求模。
is [not] div by是否能被某数整除，
is [not] even是否为偶数，
$a is [not] even by $b即($a / $b) % 2 == 0，
is [not] odd是否为奇，
$a is not odd by $b即($a / $b) % 2 != 0 示例：
equal/ not equal/ greater than/ less than/ less than or equal/ great than or equal/后面的就不用说了
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. Example 7-11. if statements
例 7-11. if 语句演示 {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,2=even,4=odd,5=odd,etc. }
{if $var is even by 3}
...
{/if}
