From: Alejandro Colomar <alx@kernel.org>
Date: Sat, 9 Dec 2023 12:35:19 +0000 (+0100)
Subject: scanf.3: BUGS: It's impossible to know how many characters were consumed
X-Git-Tag: man-pages-6.06~59
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=239c4bdd83bb09293248b93a3a218efa2d4cf017;p=thirdparty%2Fman-pages.git

scanf.3: BUGS: It's impossible to know how many characters were consumed

Suggested-by: Zack Weinberg <zack@owlfolio.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
---

diff --git a/man3/scanf.3 b/man3/scanf.3
index 63f9c6dfd7..be335a5974 100644
--- a/man3/scanf.3
+++ b/man3/scanf.3
@@ -144,6 +144,15 @@ like the standard input stream.
 .P
 These functions can't report errors after the last
 non-suppressed conversion specification.
+.SH BUGS
+It is impossible to accurately know
+how many characters these functions have consumed from the input stream,
+since they only report the number of successful conversions.
+For example,
+if the input is "123\en\ a",
+.I scanf(\[dq]%d\ %d\[dq], &a, &b)
+will consume the digits, the newline, and the space, but not the letter a.
+This makes it difficult to recover from invalid input.
 .SH SEE ALSO
 .BR fgets (3),
 .BR getline (3),