On 14/06/2017, Radoslaw Zarzynski wrote:
> This isn't a drop-in replacement for strlen(). It works differently
> for strings with \0 buried somewhere in the middle.
#include <iostream>
#include <cstdlib>
#include <stdexcept>
namespace _ {
constexpr std::size_t string_length_(const char* s, std::size_t i,
std::size_t n) {
return i < n ? (*(s + i) == '\0' ? i : string_length_(s, i + 1, n))
: throw std::invalid_argument("Unterminated string constant.");
}
}
template<std::size_t N>
constexpr std::size_t string_length(const char(&s)[N]) {
return _::string_length_(s, 0, N);
}
constexpr const char s1[] = "cat";
constexpr const char s2[] = "cat\0dog";
constexpr const char s3[3] = { 'c', 'a', 't' };
constexpr std::size_t n1 = string_length(s1);
constexpr std::size_t n2 = string_length(s2);
int main(void) {
std::cout << "string_length(s1): " << n1 << std::endl;
std::cout << "string_length(s2): " << n2 << std::endl;
try {
std::cout << "string_length(s3): " << string_length(s3) << std::endl;
} catch (const std::invalid_argument& e) {
std::cerr << "How exceptional! " << e.what() << std::endl;
}
}
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