C program Language 'EOF' and 'getchar()'

#include <stdio.h>
void main()
{
    int c;
    c=getchar();
    while(c!=EOF)
    {
            putchar(c);
            c=getchar();
    }
}

getchar() returns a distinctive value when there is no more input, a value that cannot be confused with any real character. This value is called
EOF, for ``end of file''.

Q: The type char is specifically meant for storing such character data, but any integer type can be used.
We used int for a subtle but important reason.

A: We must declare c to be a type big enough to hold any value that getchar returns. We
can't use char since c must be big enough to hold EOF in addition to any possible char. Therefore we use int.

EOF is an integer defined in <stdio.h>, but the specific numeric value doesn't matter as long as it is not the same as
any char value. By using the symbolic constant, we are assured that nothing in the program depends on the
specific numeric value.

 

The next program counts characters; it is similar to the upper case:

#include <stdio.h>
void main()
{
    int nc;
    nc=0;
    while(getchar()!=EOF)
      ++nc;
    printf("\nCharacter Counting is: %1d\n",nc);
}

[15:10:28@wjshan0808 ~/Documents/C Program]$ gcc CharactersCount.c
[15:17:38@wjshan0808 ~/Documents/C Program]$ ./a.out
asdf　　　　　　//Ctrl+D
Character Counting is: 4
[15:17:44@wjshan0808 ~/Documents/C Program]$ ./a.out
asdf　　　　　　
　　　　　　　　//Ctrl+D
Character Counting is: 5
[15:17:52@wjshan0808 ~/Documents/C Program]$