Format Specifiers in C++
When debugging native code in the Watch window or QuickWatch dialog box, you change the format in which a value is displayed using format specifiers.
(Most format specifiers are for native code only, but Visual C# has a limited set of format specifiers. For information, see Format Specifiers in C#.)
You can also use format specifiers in the Immediate window, Command window, and even in source windows. If you hover the cursor over an expression in those windows, the result will appear in a DataTip. DataTips will reflect the format specifier in the DataTip display.
Example
Suppose nVar is an integer variable, and the Watch window shows that it contains the value 0x0065. To see value expressed as a character instead of an integer, in the Name column, after the variable name, add the character format specifier, c:
nVar,c
Instead of the integer value 0x0065, the Value column now displays the character value, 101 'e'.
If you want to apply a format specifier to elements of an array or members of an object, you must apply it directly to each element or member. You cannot apply it to the array or object as a whole. For example, suppose you had an array nArray and wanted to see the first four elements in character format. You would enter these expressions in the Watch window:
nArray[0],c
nArray[1],c
nArray[2],c
nArray[3],c
The following tables show the format specifiers recognized by the debugger.
| Specifier | Format | Expression | Value Displayed |
|---|---|---|---|
d,i |
signed decimal integer |
0xF000F065, d |
-268373915 |
u |
unsigned decimal integer |
0x0065, u |
101 |
o |
unsigned octal integer |
0xF065, o |
0170145 |
x,X |
Hexadecimal integer |
61541, x |
0x0000F065 |
l,h |
long or short prefix for: d, i, u, o, x, X |
00406042,hx |
0x0c22 |
f |
signed floating point |
(3./2.), f |
1.500000 |
e |
signed scientific notation |
(3./2.), e |
1.500000e+000 |
g |
signed floating point or signed scientific notation, whichever is shorter |
(3./2.), g |
1.5 |
c |
Single character |
0x0065, c |
101 'e' |
s |
String |
0x0012fde8, s |
"Hello world" |
su |
Unicode string |
0x0012fde8, su |
"Hello world" |
hr |
HRESULT or Win32 error code. (The debugger now decodes HRESULTs automatically, so this specifier is not required in those cases. |
0x00000000L, hr |
S_OK |
wc |
Window class flag. |
0x00000040, wc |
WC_DEFAULTCHAR |
wm |
Windows message numbers |
0x0010, wm |
WM_CLOSE |
! |
raw format, ignoring any data type views customizations |
i ! |
4 |
The following table contains 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 | Expression | Value Displayed |
|---|---|---|---|
ma |
64 ASCII characters |
ptr, ma |
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 |
ptr, m |
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 |
ptr, mb |
0x0012ffac B3 34 CB 00 84 30 94 80 FF 22 8A 30 57 26 00 00 .4...0...".0W&.. |
mw |
8 words |
ptr, mw |
0x0012ffac 34B3 00CB 3084 8094 22FF 308A 2657 0000 |
md |
4 doublewords |
ptr, md |
0x0012ffac 00CB34B3 80943084 308A22FF 00002657 |
mq |
2 quadwords |
ptr, mq |
0x0012ffac 7ffdf00000000000 5f441a790012fdd4 |
mu |
2-byte characters (Unicode) |
ptr, mu |
0x0012fc60 8478 77f4 ffff ffff 0000 0000 0000 0000 |
Size Specifier for Pointers as Arrays
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:
ptr,10
See Also
Tasks
How to: Watch an Expression in the Debugger