Learn to Program with C_ Learn to Program using the Popular C Programming Language ( PDFDrive )

6.5 Read and Print Characters
Chapter 6 ■ Characters
Many programs revolve around the idea of reading and writing one character at a time, and
developing the skill of writing such programs is a very important aspect of programming. We can
use scanf to read a single character from the standard input (the keyboard) into a char variable
(ch, say) with:
scanf("%c", &ch);
The next character in the data is stored in ch. It is very important to note a big difference
between reading a number and reading a character. When reading a number, scanf will skip
over any amount of whitespace until it finds the number. When reading a character, the very next
character (whatever it is, even if it’s a space) is stored in the variable.
While we can use scanf, reading a character is important enough that C provides a special
function getchar for reading characters from the standard input. (Strictly speaking, getchar is
what’s called a macro, but the distinction is not important for our purposes.) For the most part,
we can think that getchar returns the next character in the data. However, it actually returns the
numeric code of the next character. For this reason, it is usually assigned to an int variable, as in:
int c = getchar(); // the brackets are required
But it can also be assigned to a char variable, as in:
char ch = getchar(); // the brackets are required
To be precise, getchar returns the next byte in the data – to all intents and purposes, this is
the next character. If we call getchar when there is no more data, it returns -1.
To be more precise, it returns the value designated by the symbolic constant EOF (all uppercase)
defined in stdio.h. This value is usually, though not always, -1. The actual value is system dependent,
but EOF will always denote the value returned on the system on which the program is run. We can,
of course, always find out what value is returned by printing EOF, thus:
printf("Value of EOF is %d \n", EOF);
For an example, consider the statement:
char ch = getchar();
Hello
Suppose the data typed by the user is this:
When ch = getchar() is executed, the first character H is read and stored in ch. We can
then use ch in whatever way we like. Suppose we just want to print the first character read. We
could use:
printf("%c \n", ch);
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