They are integers in integer format. (I double-checked -- they are the same size as integers.) They're no more or less numbers than 39 or 0xc0 -- none of those are how the machine really thinks of these numbers, just convenient human-readable representations.

The compiled program actually has no distinction between characters and numbers. In scripting languages and such, it's sometimes difficult to get the ASCII value of a character. In C, the ASCII value is all you ever have. Or arrays full of ASCII values.

That's my opinion, yes. Since a map is stored as a list, it has to search one-by-one, which amounts to doing this:

Code:

char trans(char c) {
        if(c == 'C') return('G');
        else if(c == 'c') return('G');
        else if(c == 'G') return('C');
        else if(c == 'g') return('C');
        else if(c == 'A') return('T');
        else if(c == 'a') return('T');
        else if(c == 'T') return('A');
        else if(c == 't') return('A');
}

...Which doesn't look that fast to me.

I could make the array even faster by removing the toupper(), and just storing m['c']='G', etc in the array too.

The first program I showed you in this thread used designated initializers:

Code:

char m[256]={ ['A']='T' };

Which is especially nice since it lets you set the values in advance without having to tell it all 256 of them. But that turned out to not be C++ compatible so I dropped it.