CODEWITHSUNDEEP
cwindowsstdineof
Mcs
Mcs

Reputation: 564

EOF in the middle of an input

my question is about how EOF is interpreted in the middle of an input, here is an example:

int main() {

  int a, b;
    printf("enter something >\n");
    scanf("%d", &a);
    while((b = getchar()) != EOF) {
      printf("%i\n", b);
    }
  return b;
 }

I run the program and enter:

 1hello^Z(control+z)abc

the output is:

 104 (ascii number for h)
 101 (for e)
 108 (l)
 108 (l) 
 111 (o)
 26 (what is this?)

The digit 1 is read by scanf, the remaining stays in the buffer, getchar() gets all of them until ^Z, which is expected behavior, as the control z closes stdin. however where does 26 come from? If the last thing getchar() reads is EOF why isn't -1 the last value? Also why doesn't this program get out of the loop when it reads ^Z, why do I need to invoke EOF one more time with control z to terminate the loop? 26 is the ascii for SUB, I don't know what to make of this.

Thank you.

Upvotes: 0

Views: 328

Answers (1)

Gaurav Jain
Gaurav Jain

Reputation: 71

When the loop ends, b=26 because you entered ctrl+z and this is interpreted as SUB while returning .http://en.wikipedia.org/wiki/Substitute_character

In the ASCII and Unicode character sets, this character(SUB) is encoded by the number 26 (1A hex). Standard keyboards transmit this code when the Ctrl and Z keys are pressed simultaneously (Ctrl+Z, by convention often described as ^Z).

Upvotes: 0

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