smarty模板引擎之if, elseif else

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.

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都是什么意思啊？

equal : 相等、not equal：不等于、greater than：大于、less than：小于、less than or equal：小于等于、great than or equal：大于等于、is even：是偶数、is odd：是奇数、is not even：不是偶数、is not odd：不是奇数、not：非、mod：取余、div by：被。。。除。

{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}