Why +1 the int

[OffKilter]

This is a borrowed function from this forum and is part of a checkers games. I've been working with it as a program to understand ASCII and Arrays.

The Line:
x=letter-'A' +1;
later...
return (x -1);


Question: Why add 1 to the value and then remove it later?

Context: User is asked to enter A - H. As a function this will be used to identify a column in an array. When I adjusted the code I removed the +1 and -1 as you can see below. Is there a reason to keep these in?

#include <iostream>
using namespace std;

int main (int argc, const char * argv[])
{

//This program asks for a letter between A - H.
//It converts the entry to uppercase and assigns the ASCII number.
//This is useful for representing a letter coordinate to an eight column array.
//Example: a checker board.

char letter;
int x = 8;

cout << "A - H: ";

//Loops until a value within range is provided
//toupper() converts the char to uppercase incase lowercase is entered

while(x<0 || x >7)
{
cin >> letter;
letter = toupper(letter);
x=letter-'A';
if (x<0 || x>7) {
cout << "Please give a letter between A - H: ";
}
}
//displays the results
cout << letter << " is column " << x << "\n";

//returns the column number (for future function use)
return(x);

}

BTW... I notice if I don't assign a value to x it defaults to 0. This "broke" the intended logic of these while() and if() statments, and maybe this is why +1 is useful?

Thanks!

[helios]

There's probably no reason other than the person liking the interval [1;8] more than [0;7].

if I don't assign a value to x it defaults to 0.

The value of an unassigned variable is an enchantment that summons the prince of darkness to eat your soul. Assume anything else at your own peril.

[OffKilter]

Okay,

that makes sense. And thanks for the warning regarding assignments. My soul is a little safer.