check string equality with const expressions [c++11]

strexpr.h

constexpr bool constStringEquals(const char * lhs, const char * rhs) {
  return (*lhs) != (*rhs)
    ? false
    : ((*lhs) == 0
      ? true
      : constStringEquals(lhs + 1, rhs + 1)
      );
}

constexpr bool constStringEndsWith(const char * str, const char * suffix) {
  return constStringEquals(str, suffix)
    ? true
    : ((*str) == 0
      ? false
      : constStringEndsWith(str+1, suffix)
      );
}

#define STATIC_ASSERT(EXPR) static_assert(EXPR, #EXPR)

STATIC_ASSERT(!constStringEquals("HELLO", "WORLD"));
STATIC_ASSERT(constStringEquals("HELLO", "HELLO"));
STATIC_ASSERT(!constStringEquals("HELLO", "HELLOHELLO"));
STATIC_ASSERT(!constStringEquals("HELLOHELLO", "HELLO"));
STATIC_ASSERT(!constStringEquals("", "WORLD"));
STATIC_ASSERT(!constStringEquals("HELLO", ""));
STATIC_ASSERT(constStringEquals("", ""));

STATIC_ASSERT(!constStringEndsWith("HELLO", "WORLD"));
STATIC_ASSERT(constStringEndsWith("HELLO", "HELLO"));
STATIC_ASSERT(!constStringEndsWith("HELLO", "HELLOHELLO"));
STATIC_ASSERT(constStringEndsWith("HELLOHELLO", "HELLO"));
STATIC_ASSERT(!constStringEndsWith("", "WORLD"));
STATIC_ASSERT(constStringEndsWith("HELLO", ""));
STATIC_ASSERT(constStringEndsWith("", ""));