.\" Copyright (c) 2022 by Alejandro Colomar .\" .\" SPDX-License-Identifier: Linux-man-pages-copyleft .\" .\" .TH EOF 3const 2023-10-31 "Linux man-pages 6.06" .SH NAME EOF \- end of file or error indicator .SH LIBRARY Standard C library .RI ( libc ) .SH SYNOPSIS .nf .B #include .P .BR "#define EOF " "/* ... */" .fi .SH DESCRIPTION .B EOF represents the end of an input file, or an error indication. It is a negative value, of type .IR int . .P .B EOF is not a character (it can't be represented by .IR "unsigned char" ). It is instead a sentinel value outside of the valid range for valid characters. .SH CONFORMING TO C99 and later; POSIX.1-2001 and later. .SH CAVEATS Programs can't pass this value to an output function to "write" the end of a file. That would likely result in undefined behavior. Instead, closing the writing stream or file descriptor that refers to such file is the way to signal the end of that file. .SH SEE ALSO .BR feof (3), .BR fgetc (3)