C语言 %ul 和 %lu C 格式说明符有什么区别？
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What's the difference between %ul and %lu C format specifiers?
提问by pedyram
In an example of "C Primer Plus", the author has used %ulformat specifier (in both scanf and printf) for unsigned long. When I try to generalize the problem, it seems that the %ulmakes something wrong in my computer. But using %lusolved the issue.
在“C Primer Plus”的一个例子中，作者%ul对unsigned long使用了格式说明符（在 scanf 和 printf 中）。当我试图概括这个问题时，似乎%ul我的电脑出了问题。但是使用%lu解决了这个问题。
Actually, rather than focusing on the problem and the line of codes, I want to know about the difference between %uland %lu. Maybe I could figure out what's wrong.
实际上，与其关注问题和代码行，我想知道%ul和之间的区别%lu。也许我可以弄清楚出了什么问题。
Searching doesn't give me something useful (except that "they are different").
搜索并没有给我一些有用的东西（除了“它们是不同的”）。
Any explanation or link/reference is appreciated.
任何解释或链接/参考表示赞赏。
回答by Jonathon Reinhart
%luis correct, while %ulis incorrect.
%lu是正确的，虽然%ul是不正确。
A printfformat specifier follows the form %[flags][width][.precision][length]specifier.
甲printf格式说明如下形式%[flags][width][.precision][length]specifier。
uis a specifiermeaning "unsigned decimal integer".
u是一个说明符，意思是“无符号十进制整数”。
lis a lengthmodifier meaning "long".
l是一个长度修饰符，意思是“长”。
The lengthmodifier should go before the conversion specifier, which means %luis correct.
该长度在转换之前修改应该去符，其手段%lu是正确的。
