Thread: while and gethchar. alternative solution.

hallo guys!
i have been studying C programming. i was typing some codes and trying to find alternative solutions about the given problem.
first of all the below code is not mine and it made me really confused.
first please check the code. and i will ask my question after.

Code:

#include <stdio.h>
int main(void){
int grade;
unsigned int acount=0;
unsigned int bcount=0;
unsigned int ccount=0;
unsigned int dcount=0;
unsigned int fcount=0;
puts("enter the letter grades");
puts("enter the E0F character to end input");

while((grade=getchar()) != E0F){
switch(grade){
case 'A':
case 'a':
++acount;
break;
case 'b':
case 'B':
++bcount;
break;
case 'C':
case 'c':
++ccount;
break;
case 'D':
case 'd':
++dcount;
break;
case 'F':
case 'f':
++fcount;
break;
default:
printf("%s","incorrect letter grade entered,enter new one");
break;
} //end switch
}// end while
puts( "\nTotals for each letter grade are:" );
printf( "A: %u\n", aCount ); // display number of A grades
printf( "B: %u\n", bCount ); // display number of B grades
printf( "C: %u\n", cCount ); // display number of C grades
printf( "D: %u\n", dCount ); // display number of D grades
 printf( "F: %u\n", fCount ); // display number of F grade
}//end main

now you understand the code. there is code for counting letter grades. my question is this
why should i need to use E0F character to stop while loop ? i mean, why i can not use simply -1 to exit this code ?
and in order to execute E0F , i should press ctrl+z, otherwise it won't work. how can i turn off this feature.

and about while and getchar, i understand , i should get an input from user, but without defining any char character how does it works ?
i mean the right code according to me should be this
char x; // i defiend a character
then
while(getchar() .... etc)
did i use int grade as a character in this form ?
thank you for your help and answers. and sorry i am a new bee

I can tell right away there is a typo in your code.

Code:

E0F is not the same as EOF.

The slash is a clear indication of a zero, so you can tell the difference from O. EOF with an O is correct.

now you understand the code. there is code for counting letter grades. my question is this
why should i need to use E0F character to stop while loop ? i mean, why i can not use simply -1 to exit this code ?
and in order to execute E0F , i should press ctrl+z, otherwise it won't work. how can i turn off this feature.

There is no turning off. There are a couple of things wrong with your thinking. 1) EOF doesn't have to be -1, it just commonly is. All that the standard requires is a negative number outside of the range of a char. (More on that later) and 2) Even when EOF happens to be -1, you still should make entering it different from a normal input. Otherwise, it gets really confusing what should happen in places where "-1" is valid input to a program.

and about while and getchar, i understand , i should get an input from user, but without defining any char character how does it works ?

But you did define the variable. It's called grade in your program. It is defined as an int, because getchar() returns an int and as a consequence, EOF is an int.

Read this please: FAQ > Definition of EOF and how to use it effectively - Cprogramming.com

thank you for all of the answers guys. it's been late . sorry. i had a tough and intense exam weeks. one after another.