String to integer recursively

#1

doubt has been commented in the code

#2

Hi Vikash,
We took str.charAt(0) - ‘0’ because the return type is int. Hence this will subtract the ascii value or ‘0’ that is 48 from the character at 0th position and return us the integer that we want.
If str.charAt(0) is 3, here 3 is a character but str.charAt(0) - ‘0’ will convert it to integer value 3.

We wrote double because when we are doing calculations Math.pow(10,str.length()-1) we can exceed the range for int and commit a mistake. That’s why we are using double. Also double x = str.charAt(0) - ‘0’ will give us the int value rather than the ascii value.