Question

I was originally parsing a file line by line using fgets().

Now I changed things so that I already have my entire file in a buffer. I still like to read that buffer line by line for parsing purposes. Is there something designed for this, or do I need to make a loop that inspects for 0x0A chars at this point?

Answer 1

memchr (with a little bit of your own wrapper code, ending with memcpy) is the exact equivalent – like fgets it takes a maximum length it will process (should be the min of the remaining input buffer size and the size of your output buffer) and scans until it hits the desired character (which will be '\n') or runs out of input/output space.

Note that for data already in a buffer in memory, though, you might want to skip the step of copying to a separate output buffer, unless you need to null-terminate the output without modifying the input. Many beginner C programmers often make the mistake of thinking they need null termination, when it would really suffice to just improve some of your interfaces to take a (pointer, length) pair, allowing you to pass/process substrings without copying them. For instance you can pass them to printf using: printf("%.*s", (int)length, start);