How to parse a string to an integer without library functions?
- by dack
Hi,
I was recently asked this question in an interview:
"How could you parse a string of the form '12345' into its integer representation 12345 without using any library functions, and regardless of language?"
I thought of two answers, but the interviewer said there was a third. Here are my two solutions:
Solution 1: Keep a dictionary which maps '1' = 1, '2' = 2, etc. Then parse the string one character at a time, look up the character in your dictionary, and multiply by place value. Sum the results.
Solution 2: Parse the string one character at a time and subtract '0' from each character. This will give you '1' - '0' = 0x1, '2' - '0' = 0x2, etc. Again, multiply by place value and sum the results.
Can anyone think of what a third solution might be?
Thanks.
