Question

On one pc i am getting this on ruby 1.8.6 and on other pc i am getting error

irb(main):001:0> buff = "12345678"
 => "12345678"
 irb(main):002:0> buff[4] =0x30
  => 48
   irb(main):003:0> buff
 => "12340678"
 irb(main):004:0> @new0 = "123456789"
 => "123456789"
  irb(main):005:0> @new0[4] = 0x30 
 => 48


 > @buff ="123456789"
 => "123456789" 
  > @buff
 => "123456789" 
 > @buff[4]= 0x30
 TypeError: can't convert Fixnum into String
from (irb):3:in `[]='
from (irb):3

  > @buff[4] = 0x30

Answer 1

Seems like you are using Ruby 1.9 in your second example. The []= method has changed and only accepts strings.

You can convert an integer value to a string using chr:

@buff[4] = 0x30.chr

And retrieve a character’s byte value with:

@buff[4].ord
# => 48