warning: array subscript has type `char'

A 'char' may be 'signed' or 'unsigned'. Most regular compilers will default to 'signed'.
So if you have an array with index 127, you increment the index and it becomes -128.
This may of course be your intention.
A 'safe' type to use for an array 

index is 'int' or 'unsigned char'.


char idx;  /// limited range
somedata[idx] = otherdata;


==> (to eliminate the warning...)


unsigned char idx;
int idx;


memo.