Explain this nested expression printf

Question

int a=5;
#include<stdio.h>
int main ()

{
  printf("%d",printf("hi!")*printf("bye"));
  return 0;
}

Output:

hi!bye9

I would like to know how the order in which the conclusion occurred. Does this mean that the printf function returns a value? What is the reason for running internal printf commands?

Answer 1

The internal order is printfnot defined. Another implementation, the same implementation with different compiler settings, or the same implementation with the same code elsewhere can result in byehi!9.

It returns 9 because it printfreturns the number of characters printed, so the two internal returns printf3 and *is the familiar multiplication operator, giving 9.

Answer 2

, , , :

printf("%d",printf("hi!")*printf("bye"));
            ^             ^
            1             2

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Answer 3

printf, -, .

, , IO , , - /, , , .

Answer 4

printf . , "!" "bye" 3 . 3 * 3 - 9

Answer 5

printf() (), . , printf().

Answer 6

hi!bye9, printf , .

http://www.cplusplus.com/reference/cstdio/printf/:

. , (ferror) .

,

printf("%d",printf("hi!")*printf("bye"));

First of all, two internal calls printfare deduced hi!, and then bye. Then, the return values ​​from these two are interpreted similarly to the following (they are multiplied together and output externally printf):

printf("%d", 3 * 3);