Example code for performing fast comparison against string literals in C++

fast_literal_compare.cc

#include <cstring>
#include <iostream>
#include <string>

template <size_t N>
bool compare(const char* s, size_t n, const char(&data)[N]) {
	// Subtract 1 from N to remove null-termination
	if (n != (N - 1)) {
		return false;
	}
	return std::memcmp(s, data, (N - 1)) == 0;
}

template <size_t N>
bool compare_prefix(const char* s, size_t n, const char(&data)[N]) {
	// Subtract 1 from N to remove null-termination
	if (n < (N - 1)) {
		return false;
	}

	return std::memcmp(s, data, (N - 1)) == 0;
}

template <size_t N>
bool compare(const std::string& s, const char(&data)[N]) {
	return compare(s.c_str(), s.size(), data);
}

template <size_t N>
bool compare_prefix(const std::string& s, const char(&data)[N]) {
	return compare_prefix(s.c_str(), s.size(), data);
}

int main(int argc, char** argv) {
	const std::string input{"failovers some_key"};

	if (compare(input, "dcp")) {
		std::cout << "Called DCP stats\n";
	} else if (compare(input, "diskinfo")) {
		std::cout << "Called diskinfo stats\n";
	} else if (compare_prefix(input, "failovers ")) {
		std::cout << "Called failover prefixed stats\n";
	}
	return 0;
}