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'.

WatchFormatCPlus1

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

WatchFormatSpecDropdown

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, c 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
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
c single character 0x0065, c 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
! raw format, ignoring any data type views customizations <customized representation> 4

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

Specifiers in bold are supported only for debugging native and C++/CLI code.

Specifier Format Original Watch Value Value Displayed
d

i
signed decimal integer 0xF000F065 -268373915
u unsigned decimal integer 0x0065 101
o unsigned octal integer 0xF065 0170145
x

X
Hexadecimal integer 61541 0x0000f065
l

h
long or short prefix for: d, i, u, o, x, X 00406042 0x0c22
f signed floating point (3./2.), f 1.500000
e signed scientific notation (3.0/2.0) 1.500000e+000
g signed floating point or signed scientific notation,
whichever is shorter
(3.0/2.0) 1.5
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

Format specifiers for memory locations in interop debugging with C++/CLI

The following table describes formatting symbols used for memory locations. You can use a memory location specifier with any value or expression that evaluates to a location.

Symbol Format Original Watch Value Value Displayed
ma 64 ASCII characters 0x0012ffac 0x0012ffac .4...0...".0W&.......1W&.0.:W..1...."..1.JO&.1.2.."..1...0y....1
m 16 bytes in hexadecimal, followed by 16 ASCII characters 0x0012ffac 0x0012ffac B3 34 CB 00 84 30 94 80 FF 22 8A 30 57 26 00 00 .4...0...".0W&..
mb 16 bytes in hexadecimal, followed by 16 ASCII characters 0x0012ffac 0x0012ffac B3 34 CB 00 84 30 94 80 FF 22 8A 30 57 26 00 00 .4...0...".0W&..
mw 8 words 0x0012ffac 0x0012ffac 34B3 00CB 3084 8094 22FF 308A 2657 0000
md 4 doublewords 0x0012ffac 0x0012ffac 00CB34B3 80943084 308A22FF 00002657
mq 2 quadwords 0x0012ffac 0x0012ffac 7ffdf00000000000 5f441a790012fdd4
mu 2-byte characters (Unicode) 0x0012ffac 0x0012ffac 8478 77f4 ffff ffff 0000 0000 0000 0000

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.