Format specifiers for C++ in the Visual Studio debugger

You can change the format in which a value is displayed in the Watch, Autos, and Locals windows by using format specifiers.

You can also use format specifiers in the Immediate window, the Command window, in tracepoints, and even in source windows. If you pause on an expression in those windows, the result appears in a DataTip. The DataTip display reflects the format specifier.

Note

When the Visual Studio native debugger changed to a new debugging engine, some new format specifiers were added and some old ones were removed. The older debugger is still used when you do interop (mixed native and managed) debugging with C++/CLI.

Set format specifiers

We'll use the following example code:

int main() {
    int my_var1 = 0x0065;
    int my_var2 = 0x0066;
    int my_var3 = 0x0067;
}

Add the my_var1 variable to the Watch window while debugging, Debug > Windows > Watch > Watch 1. Next, right-click the variable and select Hexadecimal Display. Now the Watch window shows the value 0x0065. To see this value expressed as a character rather than an integer, first right-click and deselect Hexadecimal Display. Then add the character format specifier , c in the Name column after the variable name. The Value column now shows 101 'e'.

You can view and select from a list of available format specifiers by appending a comma (,) to the value in the Watch window.

Format specifiers

The following tables describe the format specifiers that you can use in Visual Studio. Specifiers in bold are only supported for the new debugger, and not for interop debugging with C++/CLI.

Specifier	Format	Original Watch Value	Value Displayed
d	decimal integer	0x00000066	102
o	unsigned octal integer	0x00000066	000000000146
x h	hexadecimal integer	102	0xcccccccc
X H	hexadecimal integer	102	0xCCCCCCCC
xb hb	hexadecimal integer (without leading 0x)	102	cccccccc
Xb Hb	hexadecimal integer (without leading 0x)	102	CCCCCCCC
b	unsigned binary integer	25	0b00000000000000000000000000011001
bb	unsigned binary integer(without leading 0b)	25	00000000000000000000000000011001
e	scientific notation	25000000	2.500000e+07
g	shorter of scientific or floating point	25000000	2.5e+07
c	single character	0x0065	101 'e'
s	const char* string (with quotation marks)	<location> "hello world"	"hello world"
sb	const char* string (no quotation marks)	<location> "hello world"	hello world
s8	UTF-8 string	<location> "This is a UTF-8 coffee cup ☕"	"This is a UTF-8 coffee cup ☕"
s8b	UTF-8 string (no quotation marks)	<location> "hello world"	hello world
su	Unicode (UTF-16 encoding) string (with quotation marks)	<location> L"hello world"	L"hello world" u"hello world"
sub	Unicode (UTF-16 encoding) string (no quotation marks)	<location> L"hello world"	hello world
bstr	BSTR binary string (with quotation marks)	<location> L"hello world"	L"hello world"
env	Environment block (double-null terminated string)	<location> L"=::=::\\"	L"=::=::\\\0=C:=C:\\windows\\system32\0ALLUSERSPROFILE=...
s32	UTF-32 string (with quotation marks)	<location> U"hello world"	U"hello world"
s32b	UTF-32 string (no quotation marks)	<location> U"hello world"	hello world
en	enum	Saturday(6)	Saturday
hv	Pointer type - indicates that the pointer value being inspected is the result of the heap allocation of an array, for example, new int[3].	<location>{<first member>}	<location>{<first member>, <second member>, ...}
na	Suppresses the memory address of a pointer to an object.	<location>, {member=value...}	{member=value...}
nd	Displays only the base class information, ignoring derived classes	(Shape*) square includes base class and derived class information	Displays only base class information
hr	HRESULT or Win32 error code. This specifier is no longer needed for HRESULTs as the debugger decodes them automatically.	S_OK	S_OK
wc	Window class flag	0x0010	WC_DEFAULTCHAR
wm	Windows message numbers	16	WM_CLOSE
nr	Suppress "Raw View" item
nvo	Show "Raw View" item for numeric values only
!	raw format, ignoring any data type views customizations	<customized representation>	4
handle	Displays information about win32 handle	0x000000000000009c	Displays useful information about handle such as thread ID, etc.

Note

When the hv format specifier is present, the debugger attempts to determine the length of the buffer and display that number of elements. Because it is not always possible for the debugger to find the exact buffer size of an array, you should use a size specifier (pBuffer,[bufferSize]) whenever possible. The hv format specifier is useful when the buffer size is not readily available.

Size specifiers for pointers as arrays

If you have a pointer to an object you want to view as an array, you can use an integer or an expression to specify the number of array elements.

Specifier	Format	Original Watch Value	Value Displayed
n	Decimal or hexadecimal integer	pBuffer,[32] pBuffer,[0x20]	Displays pBuffer as a 32 element array.
[exp]	A valid C++ expression that evaluates to an integer.	pBuffer,[bufferSize]	Displays pBuffer as an array of bufferSize elements.
expand(n)	A valid C++ expression that evaluates to an integer	pBuffer, expand(2)	Displays the third element of pBuffer

Format specifiers for interop debugging with C++/CLI

Specifier	Format	Original Watch Value	Value Displayed
o	unsigned octal integer	0xF065	0170145
x X	Hexadecimal integer	61541	0x0000f065
c	single character	<location>	101 'e'
s	const char* (with quotation marks)	<location>	"hello world"
su	const wchar_t* const char16_t* (with quotation marks)	<location>	L"hello world"
sub	const wchar_t* const char16_t*	<location>	hello world
s8	const char* (with quotation marks)	<location>	"hello world"
hr	HRESULT or Win32 error code. This specifier is no longer needed for HRESULTs as the debugger decodes them automatically.	S_OK	S_OK
wc	Window class flag	0x00000040,	WC_DEFAULTCHAR
wm	Windows message numbers	0x0010	WM_CLOSE
!	raw format, ignoring any data type view customizations	<customized representation>	4

The d, e, f, g, h, i, l, m, ma, mb, md, mq, mu, mw, and u specifiers for native and C++/CLI code required the legacy debugger, which isn't supported in Visual Studio 2022 or later versions.

Size specifier for pointers as arrays in interop debugging with C++/CLI

If you have a pointer to an object you want to view as an array, you can use an integer to specify the number of array elements.

Specifier	Format	Expression	Value Displayed
n	Decimal integer	pBuffer[32]	Displays pBuffer as a 32-element array.