blocks|key|594976|text|输出的字符数为5。1000为4个字符。\n是一个字符。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|594977|与scanf系列函数不同，printf不会返回“项目”输出的数量。它返回实际的字符数。|594978|entityMap^0|9|4|J|2|0|1|5|D|6|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|I|$]]

The number of characters output is 5. <code>1000</code> is four characters. <code>\n</code> is one character.

<code>printf</code> doesn't return the number of "items" output like the <code>scanf</code> family of functions do for input. It returns the actual character count.

blocks|key|810637|text|内部调用首先发生，打印5个字符(\n、1、0、0、0)并返回5。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|810638|然后发生外部调用，并打印内部调用返回的5。|810639|entityMap^0|G|2|J|1|L|1|N|1|P|1|U|1|0|J|1|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]|$9|M|A|N|B|C]|$9|O|A|P|B|C]|$9|Q|A|R|B|C]|$9|S|A|T|B|C]|$9|U|A|V|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|I|$]]

The inner call happens first, prints 5 characters (<code>\n</code>, <code>1</code>, <code>0</code>, <code>0</code>, <code>0</code>) and returns <code>5</code>.

The outer call then happens, and prints the <code>5</code> that was returned by the inner call.

blocks|key|810743|text|假设表达式：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|810744|int+a=10;
printf("a=%25d",printf("b=%25d",a));|code-block|syntax|javascript|810745|输出|810746|b=10+a=4;|810747|b，因为赋值给了b，即|offset|length|style|CODE|810748|b=10;|810749|和|810750|b,=,1,0+++|810751|计数为4，并赋值给ai.e：|810752|a=4;|810753|entityMap^0|0|0|0|0|0|1|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|14|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|15|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|16|8|@$M|17|N|18|O|P]]|9|@]|A|$]]|$1|Q|3|R|5|D|7|19|8|@]|9|@]|A|$E|F]]|$1|S|3|T|5|6|7|1A|8|@]|9|@]|A|$]]|$1|U|3|V|5|D|7|1B|8|@]|9|@]|A|$E|F]]|$1|W|3|X|5|6|7|1C|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|D|7|1D|8|@]|9|@]|A|$E|F]]|$1|10|3|-4|5|6|7|1E|8|@]|9|@]|A|$]]]|11|$]]

suppose expression:

<pre><code>int a=10;
printf("a=%d",printf("b=%d",a));
</code></pre>

output 

<pre><code>b=10 a=4;
</code></pre>

<code>b</code>because of value of assigned to b i.e 

<pre><code>b=10;
</code></pre>

and 

<pre><code>b,=,1,0 
</code></pre>

count as four and assigns to the a i.e:

<pre><code>a=4;
</code></pre>

blocks|key|810517|text|您应该清楚地注意到，1000是4个字母，并且您有\n，它本身就是一个字符|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|810518|entityMap^0|A|4|O|2|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

You should clearly notice that <code>1000</code> is 4 letters and you have <code>\n</code> which it is a character by it self

blocks|key|595068|text|数字1000由四个数字组成，因此需要四个字符才能打印出来。四个字符加上换行符是五个字符。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|595069|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|$]]

The number 1000 is composed of four digits therefore it take four characters to print it.
Four character plus the line feed is five characters.

blocks|key|595200|text|在printf("%25d",printf("\n%25d",a));中，printf("\n%25d",a)将打印换行符'\n'和整数值1000，这使得总共有5个字符。首先调用第一个内部printf，打印换行符和1000，然后由外部printf打印返回值5。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|595201|entityMap^0|1|U|X|G|1J|4|1R|4|22|1|2G|6|33|6|3E|1|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]|$9|Q|A|R|B|C]|$9|S|A|T|B|C]|$9|U|A|V|B|C]|$9|W|A|X|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|G|$]]

in <code>printf("%d",printf("\n%d",a));</code> the <code>printf("\n%d",a)</code> will print a newline char <code>'\n'</code> and the integer value <code>1000</code> which makes a total of <code>5</code> characters. The first inner <code>printf</code> is called first which prints the newline and 1000, and then the returned value <code>5</code> is printed by the outer <code>printf</code>.

blocks|key|595327|text|Printf返回函数成功打印的字符数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|595328|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|$]]

Printf return the number of character successfully printed by the function.

blocks|key|810882|text|printf()返回total+no。对于在控制台上打印的字符，您将传递1000；因此第一个内部printf()函数将工作并打印1000，这里为no。字符数为4。其中一个是\n。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|810883|所以完全不是。字符数变为5，这就是它打印1000+5的原因。|810884|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|$]]

printf() returns total no. of character printed on console,
you pass 1000;
so first inner printf() function will work and print 1000,and here no. of character is 4. One is \n.

So total no. of character become 5,
that's why it print 1000 5.

blocks|key|811085|text|​|type|unstyled|depth|inlineStyleRanges|entityRanges|data|811086|📷|atomic|offset|length|811087|811088|正如你在图像中看到的，首先，最后一个printf显示了它应该显示的内容，即3223433+1233。现在，最后一个printf返回它显示的字符串/int中的字符数。然后，倒数第二个最后的printf显示12，这是最后一个printf显示的内容的长度，即3223433+1233。倒数第三个printf现在显示2，它是12的长度。因为12的长度是2，所以它接着显示，然后因为2的长度是1，所以显示1，最后再显示1，因为它是1的长度。|811089|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/6478810dc49e4bee1117e31edabdc6ab.png|imageAlt^0|0|0|1|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@$E|U|F|V|1|W]]|A|$]]|$1|G|3|4|5|6|7|X|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|Y|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|K|$L|$5|M|N|O|A|$P|Q|R|-4]]]]

<a href="https://i.stack.imgur.com/VajUl.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/VajUl.png" alt="enter image description here"></a>

As you can see in the image, first the last printf shows what's it's supposed to show i.e 3223433 1233 . Now, the last printf returns the number of characters in the string/int which it displayed. Then, the second last printf displays 12 which is the length of the whatever is displayed by last printf i.e 3223433 1233. The third last printf now displays 2 which is the length of 12. Since, length of 12 is 2, it is displayed next and then since length of 2 is 1, 1 is displayed and 1 again at last, since it's the length of 1.

blocks|key|595763|text|再补充一点，printf()返回的字符数可能取决于参数的说明符|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|595764|例如：|595765|int+a=+0xff;
printf("+:+%25i+characters\n"+,printf("%25x",a));+//prints+ff+:+2+characters
printf("+:+%25i+characters\n"+,printf("%25d",a));+//prints+255+:+3+characters|code-block|syntax|javascript|595766|entityMap^0|6|8|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|R|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|S|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|N|$]]

Just to add a bit more, the number of character returned by <code>printf()</code> may depends on the specifiers of the parameters

ex:

<pre><code>int a= 0xff;
printf(" : %i characters\n" ,printf("%x",a)); //prints ff : 2 characters
printf(" : %i characters\n" ,printf("%d",a)); //prints 255 : 3 characters
</code></pre>

The <code>printf()</code> function will return the number of characters printed. But in the code below 
why is it printing 5.

<pre><code>int a=1000;
printf("%d",printf("\n%d",a));
</code></pre>

It prints "1000" once and a space, so altogether we have 2 characters. 

It should output "1000 2". But its outputting "1000 5".

Return value of printf() function in C

printf()函数将返回打印的字符数。但是在下面的代码中，为什么要打印5。int a=1000;printf("%d",printf("\n%d",a));它打印"1000“一次和一个空格，所以我们总共有2个字符。它应该输出"1000 2“。但是它的输出是"1000 5“。

问C语言中printf()函数的返回值
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回答 10

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