GETLINE(3) Library Functions Manual GETLINE(3)

getdelim, getline — get a line from a stream

Standard C Library (libc, -lc)

#include <stdio.h>

ssize_t
getdelim(char ** restrict linep, size_t * restrict linecapp, int delimiter, FILE * restrict stream);

ssize_t
getline(char ** restrict linep, size_t * restrict linecapp, FILE * restrict stream);

The () function reads a line from stream, delimited by the character delimiter. The () function is equivalent to getdelim() with the newline character as the delimiter. The delimiter character is included as part of the line, unless the end of the file is reached.

The caller may provide a pointer to a malloced buffer for the line in *linep, and the capacity of that buffer in *linecapp. These functions expand the buffer as needed, as if via (). If linep points to a NULL pointer, a new buffer will be allocated. In either case, *linep and *linecapp will be updated accordingly.

The getdelim() and getline() functions return the number of characters written, excluding the terminating NUL character. The value -1 is returned if an error occurs, or if end-of-file is reached.

The following code fragment reads lines from a file and writes them to standard output. The fwrite() function is used in case the line contains embedded NUL characters.

char *line = NULL;
size_t linecap = 0;
ssize_t linelen;
while ((linelen = getline(&line, &linecap, fp)) > 0)
	fwrite(line, linelen, 1, stdout);

These functions may fail if:

[]
Either linep or linecapp is NULL.
[]
No delimiter was found in the first SSIZE_MAX characters.

These functions may also fail due to any of the errors specified for fgets() and malloc().

fgetln(3), fgets(3), malloc(3)

The getdelim() and getline() functions conform to IEEE Std 1003.1-2008 (“POSIX.1”).

These routines first appeared in FreeBSD 8.0.

There are no wide character versions of getdelim() or getline().

November 30, 2010 macOS 15.2