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Can someone explain why this works?
char c = '9'; int x = (int)(c - '0'); Why does subtracting '0' from an ascii code of a char result the number that that char is representing?
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And as it turns out, when you do "character math", subtracting any alphabetical character from any other alphabetical character (of the same case) results in bits being flipped in such a way that, if you were to interpret them as an int , would represent the distance between these characters.
Character arithmetic is used to implement arithmetic operations like addition and subtraction on characters in C language. It is used to manipulate the strings.
These are character (integer values) so the + or - '0' will subtract the ascii value from the left side of the expression. If you are talking about a zero and not a capital Oh, that has a decimal value of 48, so you are subtracting or adding 48.
You are casting an int (integer) ( 0 ) to a character (char). Casting means you are changing the type. Follow this answer to receive notifications.
Because the char are all represented by a number and '0' is the first of them all.
On the table below you see that:
'0' => 48 '1' => 49 '9' => 57. As a result: ('9' - '0') = (57 − 48) = 9
Source: http://www.asciitable.com
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