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c++lldb

C++ after initialize char[] and char , char shows in the char[]

I'm learning Cpp recently, and today when I use Clion to learn do some testing strange thing happened.

Here is my code


int main() {
    char c = 'b';
    char carr[1]{'a'};
    char *p1 =&(carr[0]);
    char *p2 =&c;
    return 0;
}

Complier:

4.2.1 Compatible Apple LLVM 11.0.0 (clang-1100.0.33.8)

lldb :

lldb

And here is the details of memory: enter image description here

Please help me to figure out the reasons!

Solution

  • That's the lldb data formatter for strings being a little too eager.

    People looking at char arrays in the debugger don't generally want a char[N] to print as an array of N char's, they want to see it as a string. So lldb provides a "data formatter" for char[*] that presents it as a C string. The formatter really should hand-null terminate that string at the length of the array. You can see the (overly simplistic) data formatter by doing:

    (lldb) type summary info carr
summary applied to (char [1]) carr is: `${var%s}` (hide value) (skip pointers)

    It just says start at the start of the array and print the memory as a C-string.

    You can see the real array by turning off the data formatter for char types with the --raw option when you print the variable:

    (lldb) v --raw carr
(char [1]) carr = {
  [0] = 'a'
}