C code only prints after ^Z - c

Question

I'm reading K&R's book on C and i got to this part where the output would be the number of newlines that you input.I wanted to make it so that it prints out each number corresponding to the amount of newlines typed as the lines are being read.This only outputs the value of nl after F6 or CTRL+Z has been pressed(EOF).Could someone explain to me why?
int main(){
int c, nl = 0;
while ((c = getchar()) != EOF)
if (c == '\n')
++nl;
printf("%d\n", nl);
}

Answer 1

You forgot some brackets. Here's what your code does currently:
int main(){
int c, nl = 0;
while ((c = getchar()) != EOF){
if (c == '\n'){
++nl;
}
}
printf("%d\n", nl);
}
Here's what you probably wanted to do based of indentation:
int main(){
int c, nl = 0;
while ((c = getchar()) != EOF){
if (c == '\n'){
++nl;
printf("%d\n", nl);
}
}
}
In C, whitespace is mostly ignored. If you want to run multiple statements together in a block, you need to surround that code with brackets {}

Answer 2

The while loop ends only when the character is an EOF character. EOF is a special character that represents the end of the file the program is reading. Since you are reading from the console, the console itself is the file you are reading from but it as no end. However in your system you can send an EOF character to the console by typing F6 or CTRL+Z
Instead if you want to print the number of lines while typing you should change your code like this:
int main(){
int c, nl = 0;
while ((c = getchar()) != EOF){
if (c == '\n'){
++nl;
printf("%d\n", nl);
}
}
}