[c++] How do I print the full value of a long string in gdb?

I want to print the full length of a C-string in GDB. By default it's being abbreviated, how do I force GDB to print the whole string?

There is a third option: the x command, which allows you to set a different limit for the specific command instead of changing a global setting. To print the first 300 characters of a string you can use x/300s your_string. The output might be a bit harder to read. For example printing a SQL query results in:

(gdb) x/300sb stmt.c_str()
0x9cd948:    "SELECT article.r"...
0x9cd958:    "owid FROM articl"...
..

As long as your program's in a sane state, you can also call (void)puts(your_string) to print it to stdout. Same principle applies to all functions available to the debugger, actually.

The printf command will print the complete strings:

(gdb) printf "%s\n", string

As long as your program's in a sane state, you can also call (void)puts(your_string) to print it to stdout. Same principle applies to all functions available to the debugger, actually.

Using set elements ... isn't always the best way. It would be useful if there were a distinct set string-elements ....

So, I use these functions in my .gdbinit:

define pstr
  ptype $arg0._M_dataplus._M_p
  printf "[%d] = %s\n", $arg0._M_string_length, $arg0._M_dataplus._M_p
end

define pcstr
  ptype $arg0
  printf "[%d] = %s\n", strlen($arg0), $arg0
end

Caveats:

• The first is c++ lib dependent as it accesses members of std::string, but is easily adjusted.
• The second can only be used on a running program as it calls strlen.

There is a third option: the x command, which allows you to set a different limit for the specific command instead of changing a global setting. To print the first 300 characters of a string you can use x/300s your_string. The output might be a bit harder to read. For example printing a SQL query results in:

(gdb) x/300sb stmt.c_str()
0x9cd948:    "SELECT article.r"...
0x9cd958:    "owid FROM articl"...
..

Just to complete it:

(gdb) p (char[10]) *($ebx)
$87 =   "asdfasdfe\n"

You must give a length, but may change the representation of that string:

(gdb) p/x (char[10]) *($ebx)
$90 =   {0x61,
  0x73,
  0x64,
  0x66,
  0x61,
  0x73,
  0x64,
  0x66,
  0x65,
  0xa}

This may be useful if you want to debug by their values

As long as your program's in a sane state, you can also call (void)puts(your_string) to print it to stdout. Same principle applies to all functions available to the debugger, actually.

Using set elements ... isn't always the best way. It would be useful if there were a distinct set string-elements ....

So, I use these functions in my .gdbinit:

define pstr
  ptype $arg0._M_dataplus._M_p
  printf "[%d] = %s\n", $arg0._M_string_length, $arg0._M_dataplus._M_p
end

define pcstr
  ptype $arg0
  printf "[%d] = %s\n", strlen($arg0), $arg0
end

Caveats:

• The first is c++ lib dependent as it accesses members of std::string, but is easily adjusted.
• The second can only be used on a running program as it calls strlen.

Just to complete it:

(gdb) p (char[10]) *($ebx)
$87 =   "asdfasdfe\n"

You must give a length, but may change the representation of that string:

(gdb) p/x (char[10]) *($ebx)
$90 =   {0x61,
  0x73,
  0x64,
  0x66,
  0x61,
  0x73,
  0x64,
  0x66,
  0x65,
  0xa}

This may be useful if you want to debug by their values

The printf command will print the complete strings:

(gdb) printf "%s\n", string

As long as your program's in a sane state, you can also call (void)puts(your_string) to print it to stdout. Same principle applies to all functions available to the debugger, actually.