Exercise 1-6 (getchar EOF)

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Exercise 1-6     K&R, p. 17

Exercise 1-6. Verify that the expression  getchar() !=  EOF  is 0 or 1.

test.c         download

#include <stdio.h> // for getchar(), putchar(), EOF

// test boolean value of getchar() != EOF
// true is 1 or not zero, false is 0

int main()
{
int c;

while ((c = getchar()) != EOF)
{ // print as integer:
if (c != '\n') {printf("%d", c != EOF);}
else {putchar('\n');}
}
printf("%d\n", c != EOF);
}
/*
gcc test.c -o test
./test // input from the keyboard
Hello // Enter (not EOF, but two chars)
11111
-1 // Enter
11
// Ctrl+D in Linux, Ctrl+Z then Enter in Windows (EOF)
0

./test < test.c // redirect input to source file
11...110

./test < test // input binary file
11...110
*/

Note:  1  is printed as an integer as it is different from the character '1', see the ASCII_code. Test with
putchar(49); putchar('1'); putchar('\n');

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