[C Program] Probems about "isspace"

Question

Difficulties appear in my homework again. I am writing a program to count the number of whitespace characters in a text file. I use "isspace" to count it. The content in the text file is "1 1 1", but the counter still 0, what's wrong of the codes?

#include "stdafx.h"
#include "ctype.h"
int _tmain(int argc, _TCHAR* argv[])
{

FILE* input; 
char x;
int space = 0;

input = fopen("123.txt", "r");

while ((fscanf(input, " %c", &x)) == 1)
{
   if (isspace(x)) 
   space++; 
}

printf("space : %d\n", space);

return 0;
}

Answer 1

As I've pointed out before, you need to use fgetc(), not fscanf(). fscanf() doesn't read whitepace.

Answer 2

scanf-family functions will automatically skip whitespace when it's present in the format string. Consider using fgetc instead.

Answer 3

I think using fgetc (or getc) is a better solution in this case, but the other answers are wrong about fscanf in this case. The scanf family of functions will not skip whitespace if you use "%c" as the format. The reason your call doesn't work is because you have a whitespace in your format! So, instead of " %c" as the format, you need to use "%c" without the leading space. The leading space is telling fscanf: skip all whitespace and then give me the next non-whitespace character. fscanf does this, making sure that any value you get in x is not a whitespace. Thus, your isspace test is testing a condition that is already known to be false!

You can easily fix it by changing your format specification to "%c".

Having said that, I think it's much better to use fgetc/getc anyway because, as you have found out, scanf family of functions are hard to get right.