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28 .\" @(#)fgetln.3 8.3 (Berkeley) 4/19/94
29 .\" $FreeBSD: src/lib/libc/stdio/fgetln.3,v 1.10 2009/02/28 06:00:58 das Exp $
36 .Nd get a line from a stream
42 .Fn fgetln "FILE *stream" "size_t *len"
44 Using this function is error-prone in multiple ways;
45 consider using the safer and more portable function
52 returns a pointer to the next line from the stream referenced by
56 a C string as it does not end with a terminating
59 The length of the line, including the final newline,
60 is stored in the memory location to which
63 (Note, however, that if the line is the last
64 in a file that does not end in a newline,
65 the returned text will not contain a newline.)
67 Upon successful completion a pointer is returned;
68 this pointer becomes invalid after the next
72 (whether successful or not)
73 or as soon as the stream is closed.
80 does not distinguish between end-of-file and error; the routines
85 to determine which occurred.
86 If an error occurs, the global variable
88 is set to indicate the error.
89 The end-of-file condition is remembered, even on a terminal, and all
90 subsequent attempts to read will return
92 until the condition is
96 The text to which the returned pointer points may be modified,
97 provided that no changes are made beyond the returned size.
98 These changes are lost as soon as the pointer becomes invalid.
104 is not a stream open for reading.
110 may also fail and set
112 for any of the errors specified for the routines
129 function first appeared in
132 Since the returned buffer is not a C string (it is not null terminated), a
133 common practice is to replace the newline character with
135 However, if the last line in a file does not contain a newline,
136 the returned text won't contain a newline either.
137 The following code demonstrates how to deal with this problem by allocating a
143 while ((lbuf = buf = fgetln(fp, &len)) != NULL) {
144 if (len > 0 && buf[len - 1] == '\en')
145 buf[len - 1] = '\e0';
146 else if ((lbuf = strndup(buf, len + 1)) == NULL)
148 printf("%s\en", lbuf);