Using strchr() to create multiple strings from one master string

Question

I'm working on a program in C for a class that requires me to take a request-line and break it down into its subsequent pieces. It's for learning purposes, so I can expect a fairly standard request-line.

Thinking about the problem, I was going to march through each char in the request-line with some sort of for() loop that creates a new string every time it encounters a SP, but I was wondering if there was a way to use strchr() to point to each "piece" of the request-line?

Since a request-line looks like method SP request-target SP HTTP-version CRLF where SP is a single space, is there some way I could create a function that uses strchr(request-line, ' ') to create a string (or char* or char[ ]) that then ENDS at the next SP ?

edit:

So I could do something like

char method = strchr(request-line, ' ');

But then, wouldn't "method" be every char after the SP? How can I "trim" what gets put into my variable? Or am I totally misunderstanding how this function works?

Answer 1

You can technically use strtok but it will modify the request line in place, which may be acceptable, but not in every situation. Here is a generalized solution:

char *method, *target, *version;
const char *p = request_line, *p1;

while (*p != ' ')
{
   p++;
}
method = strndup(request_line, p - request_line);
p1 = ++p;
while (*p != ' ')
{
   p++;
}
target = strndup(p1, p - p1);
p1 = ++p;
while (*p != '\r')
{
   p++;
}
version = strndup(p1, p - p1);

As you expect only well-formatted input, I omitted all error checks.