输出如何是4321 [英] How the output is 4321

问题描述

int i = 43; printf（％d，（printf（％d，（printf（％d，i）））））;



什么我试过了：



我的输出是434343.任何人都可以帮我吗

解决方案

< blockquote>不，你的输出是4321：

 printf（％d，（printf（％d，（printf（％d，i））） ））; 
 ^ ^ 
打印43并返回打印的字符数：2 
 ^ ^ 
打印2并返回打印的字符数：1 
 ^ ^ 
打印1并返回打印的字符数：1 

这相当于说：

 i = printf（％d，i）; 
 i = printf（％d，i）; 
 printf（％d，i）; 

因为必须首先执行最里面的函数调用。

看看这里< a href =http://www.cplusplus.com/reference/cstdio/printf/> printf - C ++参考 [ ^ ]

 int i = 43; 
 printf（％d，（printf（％d，（ printf（％d，i）））））; 

粗体printf首先完成并打印43，printf的返回值为2（如打印的2个字符）。

 int i = 43; 
 printf（％d，（ printf （％d，（printf（％d，i）>））））; 

这个粗体printf是下一个，操作数是2（第一次调用的返回值），因此打印数字2，此printf的返回值为1，因为只有一个字符是打印。

 int i = 43; 
  printf （％d，（printf（％d，（printf（％d，i）>））））; 

这里的粗体printf最后以数字1作为操作数，因此打印1。



所以预期的输出将是4321。

int i =43; printf("%d",(printf("%d",(printf("%d",i)))));

What I have tried:

My output is 434343. Can any one help me please

解决方案

No, your output is 4321:

printf("%d",(printf("%d",(printf("%d",i)))));
                          ^             ^
                            Prints "43" and returns the number of characters printed: 2
             ^                            ^
                Prints "2" and returns the number of characters printed: 1
^                                           ^
   Prints "1" and returns the number of characters printed: 1

It's the equivalent of saying:

i = printf("%d",i);
i = printf("%d",i);
printf("%d",i);

As the "innermost" function call has to be executed first.

Take a look here printf - C++ Reference[^]

int i =43; 
printf("%d",(printf("%d",(printf("%d",i)))));

the bold printf is done first and prints "43", the return value of the printf is 2 (as in 2 characters printed).

int i =43; 
printf("%d",(printf("%d",(printf("%d",i)>)))); 

this bold printf is next and the operand is 2 (the return value from the first call), and so the number "2" gets printed, the return value from this printf is 1 as only one character was printed.

int i =43; 
printf("%d",(printf("%d",(printf("%d",i)>))));

the bold printf here is done last with the number 1 as the operand, so "1" gets printed.

So the expected output would be "4321".

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