Question

Below is a small program that I have written to count the number of times a space, newline or tab is entered from the keyboard.

However, I don’t know what’s going wrong. I am getting my counts as zero always no matter how many spaces or newlines are inputted.

#include <stdio.h>

/*program to count blanks ,tabs and newlines */

int main()
{
       int cnt_space=0,cnt_newline=0,cnt_tab=0;
       int c;

       while(c=getchar()!=EOF)
       {
         if(c==' ')
         {
           ++cnt_space;
         }
         if(c=='\n')
         {
           ++cnt_newline;
         }
         if(c=='\t')
         {
           ++cnt_tab;
         }
       }

       printf("spaces=%d\nnewlines=%d",cnt_space,cnt_newline);
       return 0;
 }

Answer 1

Change this

while(c=getchar()!=EOF) 

to

while((c=getchar())!=EOF)

The reason why this matters is that getchar return value gets compared to EOF first, result being 0 or 1. Then the result value gets stored in c. So it would never match any of the conditions.

The reason why getchar gets compared to EOF first is because the != operator has a higher precedence than the = operator.