Parse without string split

Question

This is a spin-off from the discussion in some other question.

Suppose I\'ve got to parse a huge number of very long strings. Each string contains a sequence of

Answer 1

if you want to do it really fast, i would use a state machine

this could look like:

enum State
{
    Separator, Sign, Mantisse etc.
}
State CurrentState = State.Separator;
int Prefix, Exponent, Mantisse;
foreach(var ch in InputString)
{
    switch(CurrentState)
    { // set new currentstate in dependence of ch and CurrentState
        case Separator:
           GotNewDouble(Prefix, Exponent, Mantisse); 


    }

}