Every programming language has the function of converting string to number.

But do you know how this is done?

Actually, it’s a very simple process.

For example to the “12” string

In a loop, first, get elements in string convert to ascii code, second, ascii code – 48 (because, code 48 represents 0 in ascii table), after then result, multiplied by 10 and assigned to variable.

For that case;

10 * variable + (49 - 48)
10 * 0 (first) + 1
1

And here is another example, write with C#

(Source: My Gist)

static int intParse(string value)
{
   int newVal = 0;
   foreach (char letter in value)
   {
       newVal = 10 * newVal + (letter - 48);
   }
   return newVal;
}