Thread: i dont understand this condition

iam creating a program that the user will enter (upper/lower case) from A-H or (a-h) and someone came up with this code which i dont understand why is it (or ||), and not (and &&)

Code:

(((c >= 'A') && (c <= 'H')) || ((c >= 'a') && (c <= 'h')))

Well do you know of the ASCII format?

If not, go to www.asciitable.com

The char, declared as c is being compared to the ASCII value of the letter.

So if the user enters a character that is (greater than or equal to the value of 'A' AND less than/equal to 'H') OR ( greater than or equal to 'a' AND less than/equal to 'h')

it will do what that if statement suggests.

When doing a check for characters entered by the user, you may want to compare the ASCII values of them, because that's how the computer recognizes alphabets, they are assigned an ASCII value, for e.g. 'A' maybe assigned a value of 65.

The only way to access that ASCII value is to put the alphabet in single quotes: 'A'

You should have put this in the other thread, not started a new one.

Code:

if((a==A)||(a==H)&&(a==a)||(a==h))

That is what you put earlier. You haven't specified the range there. That will only check if the character is equal to A or equal to H, you need to specify a range, hence >= or <=

Also your && || operands had to be switched around, say it out in your head, it will make sense that way.

if you need to convert upper or lower case check out the string.h header for tolower() and toupper()
probably easier then rewriting the whole thing.

Originally Posted by joker_tony

Code:

(((c >= 'A') && (c <= 'H')) || ((c >= 'a') && (c <= 'h')))

Too many unnecessary brackets. That code is equivalent to this:

Code:

(c >= 'A' && c <= 'H' || c >= 'a' && c <= 'h')

If you prefer having unnecessary brackets, then there's certainly no need to go furthur than this:

Code:

((c >= 'A' && c <= 'H') || (c >= 'a' && c <= 'h'))

I would prefer the second because it's more explicit in telling how the expression is evaluated.