Let's say I have an array in C++:
double* velocity = new double[100];
Using the GDB command line, I can view this array with the command:
> print *velocity @ 100
and it will print a nicely-formatted list of all the double values inside the array.
However, when using the Xcode debugger, the most it will do is treat this as a pointer to a single double value, and display velocity[0] in the variable list.
This makes it a real PITA to debug programs that contain large dynamically allocated array. There has got to be some way to tell Xcode "This is a pointer to an array of length 100", and have it display the thing as such. Anyone know what it is?
I think that my answer will be a good addition for the old one.
New versions of Xcode use lldb
debugger as default tool instead of gdb
.
According this page :
With the release of Xcode 5, the LLDB debugger becomes the foundation for the debugging experience on OS X.
So for Xcode since version 5 and up I use this lldb
command:
memory read -t int -c8 `array_name`
where:
8
- the number of elements in array
array_name
- the name of array
int
- the type of array
The result of execution of this command will be something like this:
(lldb) memory read -t int -c8 array
(int) 0x7fff5fbff870 = 7
(int) 0x7fff5fbff874 = 6
(int) 0x7fff5fbff878 = 9
(int) 0x7fff5fbff87c = 10
(int) 0x7fff5fbff880 = 1
(int) 0x7fff5fbff884 = 8
(int) 0x7fff5fbff888 = 4
(int) 0x7fff5fbff88c = 3
You can use gdb syntax as expressions:
'*velocity @ 100'
at the bottom of the window (Expression:) As of Xcode 10, you can right-click velocity
, choose "View value as..." and then "Custom Type". Then cast it to (double(&)[100]) *velocity
and display the array in the GUI.
不幸的是,GUI是有限的,你需要融合GDB魔法的完美组合才能完成任务。
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