Subject: [Boost-commit] svn:boost r73705 - trunk/libs/conversion/doc
From: antoshkka_at_[hidden]
Date: 2011-08-12 13:04:31
Author: apolukhin
Date: 2011-08-12 13:04:31 EDT (Fri, 12 Aug 2011)
New Revision: 73705
URL: http://svn.boost.org/trac/boost/changeset/73705
Log:
Fixes #5746
Updates FAQ section of documentation
Text files modified:
trunk/libs/conversion/doc/lexical_cast.qbk | 18 ++++++++++++++++--
1 files changed, 16 insertions(+), 2 deletions(-)
Modified: trunk/libs/conversion/doc/lexical_cast.qbk
==============================================================================
--- trunk/libs/conversion/doc/lexical_cast.qbk (original)
+++ trunk/libs/conversion/doc/lexical_cast.qbk 2011-08-12 13:04:31 EDT (Fri, 12 Aug 2011)
@@ -118,17 +118,29 @@
[section Frequently Asked Questions]
* [*Question:] Why does `lexical_cast<int8_t>("127")` throw `bad_lexical_cast`?
- * [*Answer:] The type `int8_t` is a `typedef` to `char` or `signed char`. Lexical conversion to these types
-is simply reading a byte from source but since the source has more than one byte, the exception is thrown.
+ * [*Answer:] The type `int8_t` is a `typedef` to `char` or `signed char`. Lexical conversion to these types is simply reading a byte from source but since the source has more than one byte, the exception is thrown.
Please use other integer types such as `int` or `short int`. If bounds checking is important, you can also
call __numericcast__:
`numeric_cast<int8_t>(lexical_cast<int>("127"));`
+[pre
+]
+
+* [*Question:] Why does `lexical_cast<unsigned char>("127")` throw `bad_lexical_cast`?
+ * [*Answer:] Lexical conversion to any char type is simply reading a byte from source. But since the source has more than one byte, the exception is thrown.
+Please use other integer types such as `int` or `short int`. If bounds checking is important, you can also
+call __numericcast__:
+`numeric_cast<int8_t>(lexical_cast<int>("127"));`
+
+[pre
+]
* [*Question:] What does `lexical_cast<std::string>` of an `int8_t` or `uint8_t` not do what I expect?
* [*Answer:] As above, note that int8_t and uint8_t are actually chars and are formatted as such. To avoid
this, cast to an integer type first: `lexical_cast<std::string>(static_cast<int>(n));`
+[pre
+]
* [*Question:] The implementation always resets the `ios_base::skipws` flag of an underlying stream object.
It breaks my `operator>>` that works only in presence of this flag. Can you remove code that resets the flag?
@@ -138,6 +150,8 @@
make your `operator>>` conform to the standard.
Read a good C++ book, study `std::sentry` and [@boost:libs/io/doc/ios_state.html `ios_state_saver`].
+[pre
+]
* [*Question:] Why `std::cout << boost::lexical_cast<unsigned int>("-1");` does not throw, but outputs 4294967295?
* [*Answer:] `boost::lexical_cast` has the behavior of `std::stringstream`, which uses `num_get` functions of