Question

I know that to convert any given char to int, this code is possible [apart from atoi()]:

int i = '2' - '0';

but I never understood how it worked, what is significance of ‘0’ and I don’t seem to find any explanation on the net about that.

Thanks in advance!!

Answer 1

In C, a character literal has type int. [Character Literals/IBM]

In your example, the numeric value of '0' is 48, the numeric value of '2' is 50. When you do '2' - '0' you get 50 - 48 = 2. This works for ASCII numbers from 0 to 9.

See ASCII table to get a better picture.

Edit: Thanks to @ouah for correction.