Name: Hengyi(Carter) Huang
Email: hh548@cornell.edu

stringtolong: A function that converts a string to a
8-byte long.

The function, stringtolong, does exactly what atoi does. atoi is
a C++ built-in function that converts string to integer(int). 
So the only difference is that now the converted value is a "long"
instead of "int".

So I just copy-and-pasted the decription of "atoi" from C++
documentation and made a little modification based on that.


*** Decription of strtolong ***

This function discards whitespaces until the first non-whitespace
character is found. Then it checks the first non-whitespace
character to see if this is a plus sign or minus sign. After 
that, scan the rest of the string for as many continuous numerical
digits as possible and convert them as a numerical long value.

The string can contain additional characters after those that 
form the integral number, which are ignored and have no effect 
on the behavior of this function.

If the first sequence of non-whitespace characters in str is not 
a valid integral number, or if no such sequence exists because 
either str is empty or it contains only whitespace characters, 
no conversion is performed.

If no valid conversion could be performed, a zero value is returned. 
If the correct value is out of the range of representable values, 
LONG_MAX (9223372036854775807) or LONG_MIN (-9223372036854775809) 
is returned.

*** Limitations ***
This function treats hex numbers as invalid ones and therefore
returns zero. Octal numbers are treated as decimals and the heading
zero and ignored. For overly large/small numbers, the function
return LONG_MAX/LONG_MIN.


*** How to Run the Program ***

Execute:
    g++ test_tolong.cpp tolong.cpp -o run_tests
    ./run_tests