View array in LLDB: equivalent of GDB's '@' operator in Xcode 4.1

There are two ways to do this in lldb.

Most commonly, you use the parray lldb command which takes a COUNT and an EXPRESSION; EXPRESSION is evaluated and should result in a pointer to memory. lldb will then print COUNT items of that type at that address. e.g.

parray 10 ptr

where ptr is of type int *.

Alternatively, it can be done by casting the pointer to a pointer-to-array.

For example, if you have a int* ptr, and you want to view it as an array of ten integers, you can do

p *(int(*)[10])ptr

Because it relies only on standard C features, this method works without any plugins or special settings. It likewise works with other debuggers like GDB or CDB, even though they also have specialized syntaxes for printing arrays.

Starting with the lldb in Xcode 8.0, there is a new built-in parray command. So you can say:

(lldb) parray <COUNT> <EXPRESSION>

to print the memory pointed to by the result of the EXPRESSION as an array of COUNT elements of the type pointed to by the expression.

If the count is stored in a variable available in the current frame, then remember you can do:

(lldb) parray `count_variable` pointer_to_malloced_array

That's a general lldb feature, any command-line argument in lldb surrounded in backticks gets evaluated as an expression that returns an integer, and then the integer gets substituted for the argument before command execution.

The only way I found was via a Python scripting module:

""" File: parray.py """
import lldb
import shlex

def parray(debugger, command, result, dict):
    args = shlex.split(command)
    va = lldb.frame.FindVariable(args[0])
    for i in range(0, int(args[1])):
        print va.GetChildAtIndex(i, 0, 1)

Define a command "parray" in lldb:

(lldb) command script import /path/to/parray.py
(lldb) command script add --function parray.parray parray

Now you can use "parray variable length":

(lldb) parray a 5
(double) *a = 0
(double) [1] = 0
(double) [2] = 1.14468
(double) [3] = 2.28936
(double) [4] = 3.43404