blocks|key|1047438|text|来自MSDN：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1047439|sprintf_s和sprintf的另一个主要区别是，sprintf_s接受一个长度参数，指定以字符为单位的输出缓冲区的大小。如果缓冲区太小，无法打印文本，则将缓冲区设置为空字符串，并调用无效的参数处理程序。与snprintf不同，sprintf_s保证缓冲区将以空结束(除非缓冲区大小为零)。|1047440|因此，理想情况下，您所写的应该是正确的。|1047441|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

From MSDN:

The other main difference between sprintf_s and sprintf is that sprintf_s takes a length parameter specifying the size of the output buffer in characters. If the buffer is too small for the text being printed then the buffer is set to an empty string and the invalid parameter handler is invoked. Unlike snprintf, sprintf_s guarantees that the buffer will be null-terminated (unless the buffer size is zero).

So ideally what you've written should work correctly.

blocks|key|1055163|text|看上去你在MSVC上写什么？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1055164|我认为sprintf_s的MSDN说它断言死了，所以我不太确定您是否可以编程地捕捉到它。|1055165|正如LBushkin所建议的，您最好使用管理字符串的类。|1055166|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

Looks like you're writing on MSVC of some sort?

I think the MSDN docs for sprintf_s says that it assert dies, so I'm not too sure if you can programmatically catch that.

As LBushkin suggested, you're much better off using classes that manage the strings.

blocks|key|2573008|text|这是精心设计的。sprintf_s和*_s家族的其他函数的全部目的是捕获缓冲区溢出错误，并将它们作为先决条件违规处理。这意味着它们并不是真正可恢复的。这是专为捕获错误而设计的--如果您知道字符串对于目标缓冲区来说可能太大，就不应该调用sprintf_s。在这种情况下，首先使用strlen检查和决定是否需要修剪。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2573009|entityMap^0|8|9|I|3|39|9|3U|6|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]|$9|M|A|N|B|C]|$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|G|$]]

It's by design. The entire point of <code>sprintf_s</code>, and other functions from the <code>*_s</code> family, is to catch buffer overrun errors and treat them as precondition violations. This means that they're not really meant to be recoverable. This is designed to catch errors only - you shouldn't ever call <code>sprintf_s</code> if you know the string can be too large for a destination buffer. In that case, use <code>strlen</code> first to check and decide whether you need to trim.

blocks|key|2573041|text|请参阅TR24731的6.6.1节，它是微软实现的功能的ISO+C委员会版本。它提供了函数set_constraint_handler()、abort_constraint_handler()和ignore_constraint_handler()函数。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2573042|帕维尔·米纳耶夫(+Pavel+)的评论暗示，微软的实现不遵守TR24731提案(这是一份“第2类技术报告”)，因此你可能无法干预，或者你可能不得不做一些与TR所指的应该做的事情不同的事情。为此，仔细检查MSDN。|2573043|entityMap|0|LINK|mutability|MUTABLE|url|http://www.open-std.org/JTC1/SC22/WG14/www/docs/n1225.pdf|1|http://www.open-std.org/JTC1/SC22/WG14/^0|19|O|1Y|Q|2P|R|3|7|0|S|8|1|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]|$9|U|A|V|B|C]|$9|W|A|X|B|C]]|D|@$9|Y|A|Z|1|10]|$9|11|A|12|1|13]]|E|$]]|$1|F|3|G|5|6|7|14|8|@]|D|@]|E|$]]|$1|H|3|-4|5|6|7|15|8|@]|D|@]|E|$]]]|I|$J|$5|K|L|M|E|$N|O]]|P|$5|K|L|M|E|$N|Q]]]]

See section 6.6.1 of <a href="http://www.open-std.org/JTC1/SC22/WG14/www/docs/n1225.pdf" rel="nofollow noreferrer">TR24731</a> which is the <a href="http://www.open-std.org/JTC1/SC22/WG14/" rel="nofollow noreferrer">ISO C Committee</a> version of the functionality implemented by Microsoft. It provides functions <code>set_constraint_handler()</code>, <code>abort_constraint_handler()</code> and <code>ignore_constraint_handler()</code> functions.

There are comments from Pavel Minaev suggesting that the Microsoft implementation does not adhere to the TR24731 proposal (which is a 'Type 2 Tech Report'), so you may not be able to intervene, or you may have to do something different from what the TR indicates should be done. For that, scrutinize MSDN.

blocks|key|1055215|text|而不是sprintf_s，您可以使用snprintf+(在windows上使用_snprintf+)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1055216|#ifdef+WIN32
#define+snprintf+_snprintf
#endif

char+buffer[10];++++
int+length+=+snprintf(+buffer,+10,+"1234567890.1234567890."+);
//+unix+snprintf+returns+length+output+would+actually+require;
//+windows+_snprintf+returns+actual+output+length+if+output+fits,+else+negative
if+(length+>=+sizeof(buffer)+%7C%7C+length<0)+
{
++++/*+error+handling+*/
}|code-block|syntax|javascript|1055217|entityMap^0|3|9|I|8|13|9|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|U|8|@]|D|@]|E|$]]]|L|$]]

Instead of <code>sprintf_s</code>, you could use <code>snprintf</code> (a.k.a <code>_snprintf</code> on windows).

<pre><code>#ifdef WIN32
#define snprintf _snprintf
#endif

char buffer[10]; 
int length = snprintf( buffer, 10, "1234567890.1234567890." );
// unix snprintf returns length output would actually require;
// windows _snprintf returns actual output length if output fits, else negative
if (length &gt;= sizeof(buffer) || length&lt;0) 
{
 /* error handling */
}
</code></pre>

blocks|key|1047575|text|它适用于VC%2B%2B，甚至比使用snprintf更安全(当然比_snprintf更安全)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1047576|void+TestString(const+char*+pEvil)
{
++char+buffer[100];
++_snprintf_s(buffer,+_TRUNCATE,+"Some+data:+%25s\n",+pEvil);
}|code-block|syntax|javascript|1047577|_TRUNCATE标志指示应该截断字符串。在这种形式下，缓冲区的大小实际上不会被传入，这是(自相矛盾的！)是什么让它如此安全。编译器使用模板魔术推断缓冲区大小，这意味着它不能被错误地指定(一个令人惊讶的常见错误)。此技术可用于创建其他安全的字符串包装程序，如我在这里的博客文章中所描述的：https://randomascii.wordpress.com/2013/04/03/stop-using-strncpy-already/|offset|length|1047578|entityMap|0|LINK|mutability|MUTABLE|url|https://randomascii.wordpress.com/2013/04/03/stop-using-strncpy-already/^0|0|0|40|20|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

This works with VC++ and is even safer than using snprintf (and certainly safer than _snprintf):

<pre><code>void TestString(const char* pEvil)
{
 char buffer[100];
 _snprintf_s(buffer, _TRUNCATE, "Some data: %s\n", pEvil);
}
</code></pre>

The _TRUNCATE flag indicates that the string should be truncated. In this form the size of the buffer isn't actually passed in, which (paradoxically!) is what makes it so safe. The compiler uses template magic to infer the buffer size which means it cannot be incorrectly specified (a surprisingly common error). This technique can be applied to create other safe string wrappers, as described in my blog post here:
<a href="https://randomascii.wordpress.com/2013/04/03/stop-using-strncpy-already/" rel="noreferrer">https://randomascii.wordpress.com/2013/04/03/stop-using-strncpy-already/</a>

The following code causes an error and kills my application. It makes sense as the buffer is only 10 bytes long and the text is 22 bytes long (buffer overflow). 

<pre><code>char buffer[10]; 
int length = sprintf_s( buffer, 10, "1234567890.1234567890." ); 
</code></pre>

How do I catch this error so I can report it instead of crashing my application? 

Edit:

After reading the comments below I went with _snprintf_s. If it returns a -1 value then the buffer was not updated.

<pre><code>length = _snprintf_s( buffer, 10, 9, "123456789" );
printf( "1) Length=%d\n", length ); // Length == 9

length = _snprintf_s( buffer, 10, 9, "1234567890.1234567890." );
printf( "2) Length=%d\n", length ); // Length == -1

length = _snprintf_s( buffer, 10, 10, "1234567890.1234567890." );
printf( "3) Length=%d\n", length ); // Crash, it needs room for the NULL char 
</code></pre>

sprintf_s with a buffer too small

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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下面的代码会导致错误并杀死我的应用程序。这是有意义的，因为缓冲区只有10字节长，文本只有22字节长(缓冲区溢出)。char buffer[10];    int length = sprintf_s( buffer, 10, "1234567890.1234567890." ); 我如何捕捉这个错误，这样我就可以报告它...

问缓冲区太小的sprintf_s
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问缓冲区太小的sprintf_sEN