blocks|key|1151101|text|如果你曾经希望i18n你的程序，远离iostreams。问题是，如果句子由多个片段组成，就不可能像iostream那样正确地定位字符串。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1151102|除了消息片段的问题之外，您还有一个排序问题。考虑一份打印学生姓名和平均成绩的报告：|1151103|std::cout+<<+name+<<+"+has+a+GPA+of+"+<<+gpa+<<+std::endl;|code-block|syntax|javascript|1151104|当你把它翻译成另一种语言时，另一种语言的语法可能需要你在名字之前显示GPA。AFAIK，iostream无法对插值的值进行重新排序。|1151105|如果您想两全其美(类型安全和能够i18n)，请使用Boost.Format。|offset|length|1151106|entityMap|0|LINK|mutability|MUTABLE|url|http://www.boost.org/doc/libs/1_41_0/libs/format/index.html^0|0|0|0|0|P|C|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|X|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|Z|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|10|8|@]|9|@$M|11|N|12|1|13]]|A|$]]|$1|O|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]]]

If you ever hope to i18n your program, stay away from iostreams. The problem is that it can be impossible to properly localize your strings if the sentence is composed of multiple fragments as is done with iostream.

Besides the issue of message fragments, you also have an issue of ordering. Consider a report that prints a student's name and their grade point average:

<pre><code>std::cout &lt;&lt; name &lt;&lt; " has a GPA of " &lt;&lt; gpa &lt;&lt; std::endl;
</code></pre>

When you translate that to another language, the other language's grammar may need you to show the GPA before the name. AFAIK, iostreams has not way to reorder the interpolated values.

If you want the best of both worlds (type safety and being able to i18n), use <a href="http://www.boost.org/doc/libs/1_41_0/libs/format/index.html" rel="noreferrer">Boost.Format</a>.

blocks|key|1150953|text|我使用printf是因为我讨厌丑陋的<<cout<<语法。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1150954|entityMap^0|I|8|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

I use printf because I hate the ugly <code>&lt;&lt;cout&lt;&lt;</code> syntax.

blocks|key|1151174|text|使用boost::format。你得到了类型安全，std::string支持，像printf一样的接口，使用cout的能力，以及许多其他的好东西。你不会回去的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1151175|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Use boost::format. You get type safety, std::string support, printf like interface, ability to use cout, and lots of other good stuff. You won't go back.

blocks|key|1365997|text|没有任何理由。我认为这只是一些奇怪的思想驱使人们只使用C%2B%2B库，尽管好的旧的C库仍然有效。我是一个喜欢C%2B%2B的人，我也经常使用C函数。他们从来没有遇到过任何问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1365998|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

No reason at all. I think it's just some strange ideology that drives people towards using only C++ libraries even though good old C libs are still valid. I'm a C++ guy and I use C functions a lot too. Never had any problems with them.

blocks|key|1366341|text|总的来说，我同意(讨厌<<语法，特别是当你需要复杂的格式时)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1366342|但我应该指出安全方面的问题。|1366343|printf("%25x",2.0f)
printf("%25x+%25x",2)
printf("%25x",2,2)|code-block|syntax|javascript|1366344|可能不会被编译器注意到，但可能会使你的应用程序崩溃。|1366345|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|O|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

On the whole I agree (hate the &lt;&lt; syntax especially if you need complex formatting) 

But I should point out the safety aspects.

<pre><code>printf("%x",2.0f)
printf("%x %x",2)
printf("%x",2,2)
</code></pre>

Probably won't be noticed by the compiler but could crash your app.

blocks|key|1151293|text|使用任何适合你的需求和偏好的东西。如果你对printf感到满意，那么一定要使用它。如果你对iostreams更满意，那就坚持使用它们。最适合你的需求就混合搭配。毕竟，这是软件--有更好的方法，也有更糟糕的方法，但很少有只有一种方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1151294|分享和享受。|1151295|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Use whatever fits your needs and preferences. If you're comfortable with printf then by all means use it. If you're happier with iostreams stick to 'em. Mix and match as best fits your requirements. This is software, after all - there's better ways and worse ways, but seldom is there only ONE way.

Share and enjoy.

blocks|key|1366129|text|我经常“退回”到使用printf()，但更多的时候是使用snprintf()，以便更容易地格式化输出。在用C%2B%2B编程时，我使用了我以前编写的这个包装器，名称如下(使用上面的示例)：cout+<<+format("(%25d,%25d)\n",+x,+y);|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1366130|这里是头文件(stdiomm.h)：|1366131|#pragma+once

#include+<cstdarg>
#include+<string>

template+<typename+T>
std::basic_string<T>+format(T+const+*format,+...);

template+<typename+T>
std::basic_string<T>+vformat(T+const+*format,+va_list+args);|code-block|syntax|javascript|1366132|和源(stdiomm.cpp)：|1366133|#include+"stdiomm.h"
#include+<boost/scoped_array.hpp>
#include+<cstdio>

template+<>
std::wstring+vformat(wchar_t+const+*format,+va_list+arguments)
{
#if+defined(_WIN32)
++++int+required(_vscwprintf(format,+arguments));
++++assert(required+>=+0);
++++boost::scoped_array<wchar_t>+buffer(new+wchar_t[required+%2B+1]);
++++int+written(vswprintf(buffer.get(),+required+%2B+1,+format,+arguments));
++++assert(written+==+required);
++++return+std::wstring(buffer.get(),+written);
#else
#+++error+"No+implementation+yet"
#endif
}

template+<>
std::string+vformat(char+const+*format,+va_list+arguments)
{
#if+defined(_WIN32)
++++int+required(_vscprintf(format,+arguments));
++++assert(required+>=+0);
++++boost::scoped_array<char>+buffer(new+char[required+%2B+1]);
++++int+written(vsnprintf(buffer.get(),+required+%2B+1,+format,+arguments));
++++assert(written+==+required);
++++return+std::string(buffer.get(),+written);
#else
++++char+*buffer;
++++int+printed+=+vasprintf(&buffer,+format,+arguments);
++++assert(printed+!=+-1);
++++std::string+retval(buffer,+printed);
++++free(buffer);
++++return+retval;++++++
#endif
}

template+<typename+T>
std::basic_string<T>+format(T+const+*format,+...)
{
++++va_list+ap;
++++va_start(ap,+format);
++++std::basic_string<T>+retval(vformat(format,+ap));
++++va_end(ap);
++++return+retval;
}

template+std::wstring+format(wchar_t+const+*format,+...);
template+std::string+format(char+const+*format,+...);|1366134|更新|1366135|在阅读了其他一些答案后，我可能不得不自己切换到boost::format()！|1366136|entityMap|0|LINK|mutability|MUTABLE|url|http://www.boost.org/doc/libs/1_41_0/libs/format/index.html^0|A|8|S|A|2I|Y|0|7|9|0|0|3|B|0|0|0|N|F|N|F|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@$9|13|A|14|B|C]|$9|15|A|16|B|C]|$9|17|A|18|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|19|8|@$9|1A|A|1B|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|1C|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|1D|8|@$9|1E|A|1F|B|C]]|D|@]|E|$]]|$1|O|3|P|5|J|7|1G|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|1H|8|@]|D|@]|E|$]]|$1|S|3|T|5|6|7|1I|8|@$9|1J|A|1K|B|C]]|D|@$9|1L|A|1M|1|1N]]|E|$]]|$1|U|3|-4|5|6|7|1O|8|@]|D|@]|E|$]]]|V|$W|$5|X|Y|Z|E|$10|11]]]]

I often "drop back" to using <code>printf()</code>, but more often <code>snprintf()</code> for easier formatted output. When programming in C++ I use this wrapper I wrote a while back, called like this (to use your example as above): <code>cout &lt;&lt; format("(%d,%d)\n", x, y);</code>

Here's the header (<code>stdiomm.h</code>):

<pre><code>#pragma once

#include &lt;cstdarg&gt;
#include &lt;string&gt;

template &lt;typename T&gt;
std::basic_string&lt;T&gt; format(T const *format, ...);

template &lt;typename T&gt;
std::basic_string&lt;T&gt; vformat(T const *format, va_list args);
</code></pre>

And the source (<code>stdiomm.cpp</code>):

<pre><code>#include "stdiomm.h"
#include &lt;boost/scoped_array.hpp&gt;
#include &lt;cstdio&gt;

template &lt;&gt;
std::wstring vformat(wchar_t const *format, va_list arguments)
{
#if defined(_WIN32)
 int required(_vscwprintf(format, arguments));
 assert(required &gt;= 0);
 boost::scoped_array&lt;wchar_t&gt; buffer(new wchar_t[required + 1]);
 int written(vswprintf(buffer.get(), required + 1, format, arguments));
 assert(written == required);
 return std::wstring(buffer.get(), written);
#else
# error "No implementation yet"
#endif
}

template &lt;&gt;
std::string vformat(char const *format, va_list arguments)
{
#if defined(_WIN32)
 int required(_vscprintf(format, arguments));
 assert(required &gt;= 0);
 boost::scoped_array&lt;char&gt; buffer(new char[required + 1]);
 int written(vsnprintf(buffer.get(), required + 1, format, arguments));
 assert(written == required);
 return std::string(buffer.get(), written);
#else
 char *buffer;
 int printed = vasprintf(&amp;buffer, format, arguments);
 assert(printed != -1);
 std::string retval(buffer, printed);
 free(buffer);
 return retval; 
#endif
}

template &lt;typename T&gt;
std::basic_string&lt;T&gt; format(T const *format, ...)
{
 va_list ap;
 va_start(ap, format);
 std::basic_string&lt;T&gt; retval(vformat(format, ap));
 va_end(ap);
 return retval;
}

template std::wstring format(wchar_t const *format, ...);
template std::string format(char const *format, ...);
</code></pre>

<h2>Update</h2>

After reading some of the other answers, I might have to make a switch to <a href="http://www.boost.org/doc/libs/1_41_0/libs/format/index.html" rel="nofollow noreferrer"><code>boost::format()</code></a> myself!

blocks|key|1366541|text|这要视情况而定。没有什么是完美的。我两者都用。Streams适用于自定义类型，因为您可以重载ostream中的>>操作符。但是当涉及到空格等问题时，最好使用printf()。stringstream和like比C风格的strcat()更好。因此，请使用适合这种情况的方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1366542|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

It depends on the situation. Nothing is perfect. I use both. Streams are good for custom types as you can overload the >> operator in ostream. But when it comes to spacing and etc it's better to use printf(). stringstream and like are better than the C style strcat(). So use one that's appropriate for the situation.

blocks|key|1151483|text|我读到警告说cout和cerr对于多线程是不安全的。如果是真的，这是一个避免使用它们的好理由。注意:我在openMP中使用GNU+g%2B%2B。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1151484|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

I have read warnings saying that cout and cerr are unsafe for multithreading. If true, this is a good reason to avoid using them. Note: I use GNU g++ with openMP.

blocks|key|1151370|text|在cpp中，streams是首选，因为它们遵循cpp的面向对象范例，而且是类型安全的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1151371|另一方面，printf更像是一种函数式方法。|1151372|我能想到的在cpp代码中不使用printf的唯一原因是不是面向对象的。|1151373|这更多的是个人的选择。|1151374|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|L|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|M|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

streams are preferred in cpp as they adhere to the object oriented paradigm of cpp,
beside being type safe.

printf , on the other hand is more of a functional approach.

only reason for not using printf in cpp code that i can think of is not being object oriented.

its more of a personal choice.

I generally use <code>cout</code> and <code>cerr</code> to write text to the console. However sometimes I find it easier to use the good old <code>printf</code> statement. I use it when I need to format the output. 

One example of where I would use this is:

<pre><code>// Lets assume that I'm printing coordinates... 
printf("(%d,%d)\n", x, y);

// To do the same thing as above using cout....
cout &lt;&lt; "(" &lt;&lt; x &lt;&lt; "," &lt;&lt; y &lt;&lt; ")" &lt;&lt; endl;
</code></pre>

I know I can format output using <code>cout</code> but I already know how to use the <code>printf</code>. Is there any reason I shouldn't use the <code>printf</code> statement?

Should I use printf in my C++ code?

我通常使用cout和cerr向控制台写入文本。但是，有时我发现使用很好的老printf语句更容易。当我需要格式化输出时，我会使用它。我使用它的一个例子是：// Lets assume that I'm printing coordinates... printf("(%d,%d)\n", x, y);// To do the same thing as above using cout....co

问我应该在我的C++代码中使用printf吗？
EN

回答 10

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问我应该在我的C++代码中使用printf吗？EN

回答 10

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问我应该在我的C++代码中使用printf吗？
EN