132 lines
6.0 KiB
Markdown
132 lines
6.0 KiB
Markdown
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# Print Format Specifiers
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## Lookup Table
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We use the following format specifiers for all \*printf\* and WLog_* functions:
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| Type | signed | unsigned | octal | hex | HEX |
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| ------------------ | --------- | --------- | --------- | --------- | --------- |
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| signed char | %hhd | | | | |
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| unsigned char | | %hhu | %hho | %hhx | %hhX |
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| short | %hd | | | | |
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| unsigned short | | %hu | %ho | %hx | %hX |
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| int | %d | | | | |
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| unsigned int | | %u | %o | %x | %X |
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| long | %ld | | | | |
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| unsigned long | | %lu | %lo | %lx | %lX |
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| long long | %lld | | | | |
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| unsigned long long | | %llu | %llo | %llx | %llX |
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| size_t | | %"PRIuz" | %"PRIoz" | %"PRIxz" | %"PRIXz" |
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| INT8 | %"PRId8" | | | | |
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| UINT8 | | %"PRIu8" | %"PRIo8" | %"PRIx8" | %"PRIX8" |
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| BOOLEAN | | %"PRIu8" | %"PRIo8" | %"PRIx8" | %"PRIX8" |
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| BYTE | | %"PRIu8" | %"PRIo8" | %"PRIx8" | %"PRIX8" |
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| CHAR | %"PRId8" | | | | |
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| UCHAR | | %"PRIu8" | %"PRIo8" | %"PRIx8" | %"PRIX8" |
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| INT16 | %"PRId16" | | | | |
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| UINT16 | | %"PRIu16" | %"PRIo16" | %"PRIx16" | %"PRIX16" |
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| WORD | | %"PRIu16" | %"PRIo16" | %"PRIx16" | %"PRIX16" |
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| WCHAR | | %"PRIu16" | %"PRIo16" | %"PRIx16" | %"PRIX16" |
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| SHORT | %"PRId16" | | | | |
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| USHORT | | %"PRIu16" | %"PRIo16" | %"PRIx16" | %"PRIX16" |
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| INT32 | %"PRId32" | | | | |
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| UINT32 | | %"PRIu32" | %"PRIo32" | %"PRIx32" | %"PRIX32" |
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| INT | %"PRId32" | | | | |
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| UINT | | %"PRIu32" | %"PRIo32" | %"PRIx32" | %"PRIX32" |
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| LONG | %"PRId32" | | | | |
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| HRESULT | %"PRId32" | | | %"PRIx32" | %"PRIX32" |
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| NTSTATUS | %"PRId32" | | | %"PRIx32" | %"PRIX32" |
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| ULONG | | %"PRIu32" | %"PRIo32" | %"PRIx32" | %"PRIX32" |
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| DWORD | | %"PRIu32" | %"PRIo32" | %"PRIx32" | %"PRIX32" |
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| DWORD32 | | %"PRIu32" | %"PRIo32" | %"PRIx32" | %"PRIX32" |
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| BOOL | %"PRId32" | | | | |
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| INT64 | %"PRId64" | | | | |
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| LONG64 | %"PRId64" | | | | |
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| LONGLONG | %"PRId64" | | | | |
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| UINT64 | | %"PRIu64" | %"PRIo64" | %"PRIx64" | %"PRIX64" |
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| ULONG64 | | %"PRIu64" | %"PRIo64" | %"PRIx64" | %"PRIX64" |
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| ULONGLONG | | %"PRIu64" | %"PRIo64" | %"PRIx64" | %"PRIX64" |
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| DWORDLONG | | %"PRIu64" | %"PRIo64" | %"PRIx64" | %"PRIX64" |
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| QWORD | | %"PRIu64" | %"PRIo64" | %"PRIx64" | %"PRIX64" |
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| ULONG64 | | %"PRIu64" | %"PRIo64" | %"PRIx64" | %"PRIX64" |
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## Pointers
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When printing pointers you should cast the argument to ``(void*)``:
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```c
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rdpContext *pContext;
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fprintf(stderr, "rdp context is %p\n", (void*) pContext);
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```
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If you need more formatting options cast the pointer argument to `size_t` and use
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any %"PRI*z" format specifier:
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```c
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rdpContext *pContext;
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fprintf(stderr, "rdp context is %" PRIuz " (0x%" PRIXz ")\n", (size_t) pContext, (size_t) pContext);
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```
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## Integer Promotion
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Remember that integer types smaller than int are promoted when an operation is
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performed on them.
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Wrong:
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```c
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UINT8 a, b;
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fprintf(stderr, "a - b is %" PRIu8 "\n", a - b);
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// depending on the system's PRIu8 definition you might get:
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// warning: format specifies type 'unsigned char' but the argument has type 'int'
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```
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Correct:
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```c
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UINT8 a, b;
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fprintf(stderr, "a - b is %d\n", a - b);
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// or ...
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fprintf(stderr, "a - b is %" PRIu8 "\n", (UINT8) (a - b));
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```
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## TCHAR
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When using `_tprintf` or similar TCHAR formatting functions or macros you
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need to enclose the PRI format defines:
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```c
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LPCTSTR lpFileName1;
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UINT64 fileSize1;
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_tprintf(_T("The size of %s is %") _T(PRIu64) _T("\n"), lpFileName1, fileSize1);
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```
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Since this makes the strings a lot harder to read try to avoid _tprintf if the
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arguments don't contain TCHAR types.
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Note: If all compilers were C99 compliant we could simply write ...
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```c
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_tprintf(_T("The size of %s is %") PRIu64 "\n"), lpFileName1, fileSize1);
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```
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... since the standard says that only one of the character sequences must be
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prefixed by an encoding prefix and the rest of them are treated to have the
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same. However, Microsoft Visual Studio versions older than VS 2015 are not C99
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compliant in this regard.
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See [How to use stdint types with _tprintf in Visual Studio 2013](http://stackoverflow.com/questions/41126081/how-to-use-stdint-types-with-tprintf-in-visual-studio-2013)
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for more information.
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## Links
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- [[MS-DTYP] 2.2 Common Data Types](https://msdn.microsoft.com/en-us/library/cc230309.aspx)
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- [Understand integer conversion rules](https://www.securecoding.cert.org/confluence/display/c/INT02-C.+Understand+integer+conversion+rules)
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- [Printf format strings](https://en.wikipedia.org/wiki/Printf_format_string)
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- [C data types - Basic Types](https://en.wikipedia.org/wiki/C_data_types#Basic_types)
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