how can I convert character to integer number

Question

How could I change an array of character (string) to an integer number without using any ready function (ex atoi();) for example :-

 char a[5]=\'4534\';
         


        

Answer 1

Without using any existing libraries, you have to:

1. Convert character to numeric digit.
2. Combine digits to form a number.

Converting character to digit:

digit = character - '0';

Forming a number:

number = 0;
Loop:
number = number * 10 + digit;

Your function will have to check for '+' and '-' and other non-digits characters.