strstr faster than algorithms?

Question

I have a file that\'s 21056 bytes.

I\'ve written a program in C that reads the entire file into a buffer, and then uses multiple search algorithms to search the file

Answer 1

Without seeing your code, it's hard to say exactly. strstr is heavily optimized, and usually written in assembly language. It does things like reading data 4 bytes at a time and comparing them (bit-twiddling if necessary if the alignment isn't right) to minimize memory latency. It can also take advantage of things like SSE to load 16 bytes at a time. If your code is only loading one byte at a time, it's probably getting killed by memory latency.

Use your debugger and step through the disassembly of strstr -- you'll probably find some interesting things in there.