getc Vs getchar Vs Scanf for reading a character from stdin

Question

Of the below three functions:

getc getchar & scanf

which is the best one for reading a character from stdin and why?

Are there any known disadvantages or limitations for any of these functions which makes one better than the other?

Darlenedarline

Answer 1

If you simply want to read a single character from stdin, then getchar() is the appropriate choice. If you have more complicated requirements, then getchar() won't be sufficient.

• getc() allows you to read from a different stream (say, one opened with fopen());
• scanf() allows you to read more than just a single character at a time.

The most common error when using getchar() is to try and use a char variable to store the result. You need to use an int variable, since the range of values getchar() returns is "a value in the range of unsigned char, plus the single negative value EOF". A char variable doesn't have sufficient range for this, which can mean that you can confuse a completely valid character return with EOF. The same applies to getc().

Chappell

Thanks for the reply. In scanf if I give only %c, then I should be able to read only one character right? – Darlenedarline

Yes, but it is overkill for that purpose. – Chappell

Seriously overkill. On many platforms, getchar() is a macro that quickly returns a character (with a buffered stream), or uses fread() to get a character. With scanf(), there's a lot of unnecessary work. – Vlf

Answer 2

from Beej's Guide to C Programming

All of these functions in one way or another, read a single character from the console or from a FILE. The differences are fairly minor, and here are the descriptions:

getc() returns a character from the specified FILE. From a usage standpoint, it's equivalent to the same fgetc() call, and fgetc() is a little more common to see. Only the implementation of the two functions differs.

fgetc() returns a character from the specified FILE. From a usage standpoint, it's equivalent to the same getc() call, except that fgetc() is a little more common to see. Only the implementation of the two functions differs.

Yes, I cheated and used cut-n-paste to do that last paragraph.

getchar() returns a character from stdin. In fact, it's the same as calling getc(stdin).

Sazerac