Like this:

My ASCII Chart

    0   1   2   3   4   5   6   7   8   9   A   B   C   D   E   F
0  NUL SOH STX ETX EOT ENQ ACK BEL BS  HT  LF  VT  FF  CR  SO  SI
1  DLE DC1 DC2 DC3 DC4 NAK SYN ETB CAN EM  SUB ESC FS  GS  RS  US
2   SP  !   "   #   $   %   &   '   (   )   *   +   ,   -   .   /
3   0   1   2   3   4   5   6   7   8   9   :   ;      ?
4   @   A   B   C   D   E   F   G   H   I   J   K   L   M   N   O
5   P   Q   R   S   T   U   V   W   X   Y   Z   [   \   ]   ^   _
6   `   a   b   c   d   e   f   g   h   i   j   k   l   m   n   o
7   p   q   r   s   t   u   v   w   x   y   z   {   |   }   ~ DEL

I want to call a function, alter the ASCII sequence in this function and when it returns, the ASCII sequence back to the original.

Thanks in advance!

EDIT:

What I want is it: I want to change the order of chars, for examble, A is 65, if I want to make A equal a 0? without to make a function to do it, for example, I could accomplish it with a function that compare an array of chars, and store it in another way with the correct value (the new table), but do it is too expensive, is there another way?

thanks in advance again!