I am just baffled by basic stream handling in C. Even after an hour of googling and reading on the issue I am none the wiser ( and it is not my first attempt to delve into this).
I am trying to read numbers from input until EOF or non-number is reached and be able to distinguish between those 2. From what I understand this should work, but the feof
and ferror
conditions are never true. Why is that ? And could somebody provide me with a working code snippet along with a dummy friendly in-depth explanation?
#include <stdio.h>
#include <stdlib.h>
int main()
{
int number;
printf("number or EOF:\n");
while(scanf("%d",&number) == 1)
{
printf("read number %d\n",number);
}
if(ferror(stdin))printf("error reading\n");
else if (feof(stdin))printf("eof reached\n");
return 0;
}
My problem understanding the stream behaviour i was getting stemmed from one little peculiarity. I didnt know that in Windows console there is a newb unfriendly ambiguity , Ctrl+Z can be as read ASCII 0x1A if you enter input like 12 23 ^Z/enter/ but gets read as proper EOF, when you do 12 23 /enter/^Z/enter/. this code solves the issue
#include <stdio.h>
#include <stdlib.h>
int main()
{
printf("int or eof\n");
int num;
while( scanf("%d",&num) ==1 )
{
printf("the read number is %d \n",num);
}
if(!feof(stdin) && getchar()!=0x1A)//first check if its read as EOF,
//if it fails, call getchar for help to check for ^Z
{
printf("non-int error\n");
}
else printf("eof ok\n");
system("PAUSE");
return 0;
I am sorry for the misleading question.