I'm reading The C Programming Language and have understood everything so far.
However when I came across the getchar()
and putchar()
, I failed to understand what is their use, and more specifically, what the following code does.
main()
{
int c;
while ((c = getchar()) != EOF)
putchar(c);
}
I understand the main()
function, the declaration of the integer c
and the while
loop. Yet I'm confused about the condition inside of the while
loop. What is the input in this C code, and what is the output.
Sorry if this is a basic and stupid question, but I'm just looking for a simple explanation before I move on in the book and become more confused.
This code can be written more clearly as:
main()
{
int c;
while (1) {
c = getchar(); // Get one character from the input
if (c == EOF) { break; } // Exit the loop if we receive EOF ("end of file")
putchar(c); // Put the character to the output
}
}
The EOF
character is received when there is no more input. The name makes more sense in the case where the input is being read from a real file, rather than user input (which is a special case of a file).
main
function should be written as int main(void)
.]