How to see actual value of a C++ string in CLion's debugger?

Question

I'm using CLion on Linux and having difficulties with debugging. I evaluated an expression which ends up being a string, but the debugger is useless at showing me what the return value is, other than that it is a string. How do I see the actual value? (also note it doesn't even show the value of char values)

Ossiferous

Please check that Enable GNU C++ Value Renderers option is on in Settings -> Build, Execution, Deployment -> Debugger. – Jodiejodo

@EldarAbusalimov I have enabled that, but all I got is random hexadecimal value, not the real one. – Rieger

@Rieger Could you check a workaround suggested in youtrack.jetbrains.com/issue/CPP-6828 (add_definitions(-D_GLIBCXX_USE_CXX11_ABI=0))? Does it help? – Jodiejodo

I know old question, but just refer to this issue here. – Racer

Answer 1

With gdb you can print std::string by below 2 methods.

1. p mystr.c_str() -this can be used to print value of type std::string.
2. p *(char**) 0x7f8fbb7a9c20 -this works for a memory with type std::string.

Aras

It’s 2020, and this is how we have to print std::string Values in a debugger: p *(char**) 0x7f8fbb7a9c20... – Cu

Answer 2

It seems like a bug of LLDB. You can check this issue: https://youtrack.jetbrains.com/issue/CPP-13701

I have tried GDB, and it works well, so you can switch to GDB toolchains to avoid this problem.

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However, in 2021, if you have to use LLDB, you can use the memory address of the variable std::string mystr;

• In LLDB console: p *(char**) &mystr
• Or, add this expression *(char**) &mystr into the watcher window of CLion-2021 debugger

Ratcliff

Answer 3

Just add a watch for a desired std::string expression and edit the watch to append .c_str() (F2 will work fine for that).

E.g. for examining the my_cpp_str variable, add the following watch:

my_cpp_str.c_str()

Haugen