CODEWITHSUNDEEP
c++cdebugginglldb
ismatim
ismatim

Reputation: 186

Display a pointer value with lldb debugger

I'm working in a personal project of open-source technologies developing an application build it in C. I'm using the lldb debugger tool.

My question is simple: How can I display or show the values of an element when I'm debugging.

For example:

#include <iostream.h>

int main(){

 char phrase[1024];
 int i=0;

 for(i=0;i<1024;i++){
    printf("%c",phrase[i]);
 }
 return 0;
}

In the lldb prompt, I can see the values for specific character of the array:

lldb>b 6
lldb>frame variable phrase[0];

When I want to execute:

lldb>frame variable phrase[i]

I got an error: "unable to find any variable expression path that matches 'phrase[i]'"

Upvotes: 3

Views: 10284

Answers (1)

Enrico Granata
Enrico Granata

Reputation: 3339

You need to use

(lldb) expr phrase[i]

or equivalently

(lldb) p phrase[i]

for that

frame variable supports constant indexes (i.e. plain ol’ numbers), but if you need to use a variable or anything BUT a number, you need to use the expression command

As a caveat, the behavior of frame var vs. expression might be different in some cases when doing array-like access. This won’t affect your example (but it would if you were using an std::vector, for instance).

Upvotes: 3

Related Questions