How many times the value of inner loop's variable is changed

auto_gdb_kuku.rb

#!/usr/bin/env ruby

# auto_gdb_kuku.rb
#   How many times the value of inner loop's variable is changed
#   by takehikom

# ruby auto_gdb_kuku.rb
# ruby auto_gdb_kuku.rb | grep 'New value'
# ruby auto_gdb_kuku.rb | grep 'New value' | wc -l

# Thanks:
# http://takuya-1st.hatenablog.jp/entry/20110919/1316426672
# http://futurismo.biz/archives/1286

require "pty"
require "expect"

imax = (ARGV.shift || 9).to_i
jmax = (ARGV.shift || imax).to_i

ccode = DATA.read
if imax != 9
  ccode["i <= 9"] = "i <= #{imax}"
end
if jmax != 9
  ccode["j <= 9"] = "j <= #{jmax}"
end
puts "% cat kuku.c"
print ccode
open("kuku.c", "w") { |f_out|
  f_out.print ccode
}
cmd = "gcc -g -O0 -o kuku kuku.c"
puts "% " + cmd
system cmd

input_lines = ["b 7", "r"]
input_lines << "watch j"
input_lines << "c"
input_lines += ["c"] * ((jmax + 1) * imax)
input_lines << "c"
input_lines << "q"

cmd = "gdb kuku"
puts "% " + cmd

PTY.getpty(cmd) do |i, o|
  o.sync = true
  $expect_verbose = true

  until input_lines.empty?
    i.expect("(gdb)", 1) { |line|
      o.puts input_lines.shift
    }
  end
end

__END__
#include <stdio.h>

int main(void)
{
  int i = 0, j = 0;

  for (i = 1; i <= 9; i++) {
    for (j = 1; j <= 9; j++) {
      printf("%2d ", i * j);
    }
    printf("\n");
  }

  return 0;
}