From: gmspro gmspro <lists@...>
Date: 2012-06-22T13:55:40+09:00
Subject: How to debug ruby source code using gdb?, can't print array content

I tried something like this in array.c

rb_ary_initialize(int argc, VALUE *argv, VALUE ary)
{
  long len;
  int ln;
  int *ar;
  VALUE size, val;
  switch (TYPE(ary)) {
    case T_FIXNUM:
      break;
    case T_STRING:
      break;
    case T_ARRAY:
      ar=RARRAY(ary);
      ln=RARRAY_LEN(ary);
      printf("ln: %d\n",ln);
      ar=RARRAY_PTR(ary);
      break;
    default:
      rb_raise(rb_eTypeError, "not valid value");
      break;
  }


gdb ./ruby
(gdb)run
ctrl+c
(gdb)break array.c:rb_ary_initialize
(gdb)continue
arr=Array.new(3)
arr[0]=5
arr[1]=7
ctrl+d
(gdb)next

But i can't understand how to print the value using printf(); in
array.c:rb_ary_initialize function doing some casting.

Can anyone post reply with example to do it?

https://github.com/ruby/ruby/blob/0b0dea752c0ef35d1a964b812a1a7fd033ab9e2e/README.EXT#L125

https://github.com/ruby/ruby/blob/0b0dea752c0ef35d1a964b812a1a7fd033ab9e2e/array.c#L569

Thanks.

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