Text conversion

Question

Hello Everybody!

I thought someone could help me with the following text conversion: a text has to be converted in accordance with a conversion table, which might look like that:
'a' -> 'b', 'c' -> 'd', etc. That is, one symbol is substituted with another according to the table.

My questions are: how can I build the conversion table (an array?, a structure?) and how can I further implement it into a conversion method?

Thank you,
Stig