Function IsDigit

src/util/strencodings.h:136–139

* Tests if the given character is a decimal digit. * @param[in] c character to test * @return true if the argument is a decimal digit; otherwise false. */

 * @return          true if the argument is a decimal digit; otherwise false.
 */
constexpr bool IsDigit(char c)
{
    return c >= '0' && c <= '9';
}

/**
 * Tests if the given character is a whitespace character. The whitespace characters