7. 内置函数 - {if},{elseif},{else} - 《Smarty3 手册》

{if},{elseif},{else}

{if},{elseif},{else}

Smarty的{if}条件判断和PHP的if 非常相似，只是增加了一些特性。每个{if}必须有一个配对的{/if}. 也可以使用{else} 和 {elseif}. 全部的PHP条件表达式和函数都可以在if内使用，如||, or, &&, and, is_array(), 等等.

如果开启了安全机制，那么只有在$php_functions设置允许的PHP函数才能使用。参见安全机制。

下面是可用的运算符列表，使用中都会放到元素的中间并且用空格分隔。注意列表中[方括号]的是可选的，而且还会列出对应PHP的表达式。

运算符	别名	语法示例	含义	对应PHP语法
==	eq	$a eq $b	等于	==
!=	ne, neq	$a neq $b	不等于	!=
>	gt	$a gt $b	大于	>
<	lt	$a lt $b	小于	<
>=	gte, ge	$a ge $b	大于等于	>=
<=	lte, le	$a le $b	小于等于	<=
===		$a === 0	绝对等于	===
!	not	not $a	非 (一元运算)	!
%	mod	$a mod $b	取模	%
is [not] div by		$a is not div by 4	取模为0	$a % $b == 0
is [not] even		$a is not even	[非] 取模为0 (一元运算)	$a % 2 == 0
is [not] even by		$a is not even by $b	水平分组 [非] 平均	($a / $b) % 2 == 0
is [not] odd		$a is not odd	[非] 奇数 (一元运算)	$a % 2 != 0
is [not] odd by		$a is not odd by $b	[非] 奇数分组	($a / $b) % 2 != 0

Example 7.44. {if} 表达式

{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}
 
 
{* 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}
 
{* check for array. *}
{if is_array($foo) }
   .....
{/if}
 
{* check for not null. *}
{if isset($foo) }
   .....
{/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}

Example 7.45. {if} 的更多例子

 
{if isset($name) && $name == 'Blog'}
     {* do something *}
{elseif $name == $foo}
    {* do something *}
{/if}
 
{if is_array($foo) && count($foo) > 0}
    {* do a foreach loop *}
{/if}

原文: https://www.smarty.net/docs/zh_CN/language.function.if.tpl