JSTL c：forEach，递减循环不可能？ [英] JSTL c:forEach, decremental number loop impossible?

问题描述

 < c：forEach var =ibegin =10 end =0step = -  1> 
 ... $ {i} ... 
< / c：forEach> 
  

然后我得到了jsp异常：

  javax.servlet.jsp.JspTagException：'step'< = 0 
 javax.servlet.jsp.jstl.core.LoopTagSupport.validateStep（LoopTagSupport.java:459）
 org.apache.taglibs.standard.tag.rt.core.ForEachTag.setStep（ForEachTag.java:60）
 .... 
  

但是这个答案表示可以循环两种方式：

JSTL forEach逆序

我有什么问题吗？

解决方案

我不确定其他问题的回答者是如何工作的，但是我不能用引用JSTL

无论如何，您可以通过以下方式达到要求：

 < c：forEach var =ibegin =0end =10step =1> 
 ... $ {10  -  i} ... 
< / c：forEach> 
  

或者如果您想避免重复 10 $ b $ $ $ p $ < c：forEach var =ibegin =0end =10step = 1varStatus =loop>
... $ {loop.end - i + loop.begin} ...
< / c：forEach>


I want to print decremental numbers like:

<c:forEach var="i" begin="10" end="0" step="-1">
    ... ${i} ...
</c:forEach>

then I got jsp exception:

javax.servlet.jsp.JspTagException: 'step' <= 0
    javax.servlet.jsp.jstl.core.LoopTagSupport.validateStep(LoopTagSupport.java:459)
    org.apache.taglibs.standard.tag.rt.core.ForEachTag.setStep(ForEachTag.java:60)
    ....

but this answer says it is possible to loop in both ways:

JSTL forEach reverse order

What's wrong with me?

解决方案

I am not sure how the answerer of the other question got it to work, but I can't get it to work here with the reference JSTL implementation.

Anyway, you can achieve the requirement with following:

<c:forEach var="i" begin="0" end="10" step="1">
    ... ${10 - i} ...
</c:forEach>

Or if you'd like to avoid duplication of 10:

<c:forEach var="i" begin="0" end="10" step="1" varStatus="loop">
    ... ${loop.end - i + loop.begin} ...
</c:forEach>

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