convert an alpha character from commandline to equivalent ASCII integer

I am trying to read an input from commandline e.g ./make DOOD
Specifically, I want to loop through DOOD and take the ASCII value of character "D" convert it to a variable say V and add V to a number say 5 and output a character G which is the sum of ascii values " V+5" so that I have

G = V+5
printf("%c", G)

Thanks

A char already is a small integer. so char ch = 'D' and char ch = 68 are exactly equivalent. You can manipulate chars by adding or subtracting values from them, just like integers, and you can convert to and from int. You can even multiply or divide (though it's hard to see where that would make sense).

Thanks Malcom. Appreciate it. My programme now works