atoi() modified to work with positive and negative numbers

[HeberDamianAlturria]

To whom it may concern,
my name is Heber Damián Alturria and i have noticed that atoi() only return 0 when we pass as input a string that represent a negative number such as "-1" or if it have a positive sign such as "+1".
To solve the aforementioned situation, i have modified the implementation of atoi() to permit the use of positive and negative signs, resulting in results as interesting as:

• atoi("204") is going to return the number 204.
• atoi("-21") is going to return the number -21.
• atoi("0") is going to return the number 0.
• atoi("+123") is going to return the number 123.
• atoi("+00000001") is going to return the number 1.
• atoi("-000000012") is going to return the number -12.

As you can appreciate, the operation of the atoi() that I have modified is similar to the atoi() provided by the C library called stdlib.h.

thank you very much for reading and I hope you will consider adding the modification I have provided to the atoi().

best regards.