如何退出while循环？

Question

#include <stdio.h>
main(void) {
   char ch;
   while (1) {   
      if ((ch = getchar()) != EOF) 
      {
         break;
      }
      putchar(ch);
   }
   return 0;
}

How do I escape from this while ? I had tried with EOF but it didn't work.

Answer 1

I think you mean:

int ch;

Because EOF won't fit in a char .

Also:

if ((ch=getchar()) == EOF)
       break;

Your logic is backwards.

Answer 2

This:

char ch;

is wrong, EOF doesn't fit in a char . The type of getchar() 's return value is int so this code should be:

int ch;

Also, as pointed out, your logic is backwards. It loop while ch is not EOF , so you can just put it in the while :

while((ch = getchar()) != EOF)

Answer 3

check with the while. It's more simple

while((ch=getchar())!= EOF) {
     putchar(ch);
}

The EOF is used to indicate the end of a file. If you are reading character from stdin, You can stop this while loop by entering:

• EOF = CTRL + D (for Linux)

• EOF = CTRL + Z (for Windows)

  You can make your check also with Escape chracter or \\n charcter

Example

while((ch=getchar()) != 0x1b) { // 0x1b is the ascii of ESC
     putchar(ch);
}