正则表达式不起作用 C++

Question

im trying to use a regular expression to ensure the heading entered for an aircraft is between o and 360, but i cant get it to work.

std::regex headingCheck{"^([0-9]|1[0-9]2[0])$"};
    bool match = false;
    while (!match)
    {
        if (std::regex_match(heading, headingCheck))
        {
            heading_ = heading;
        }
        else
        {
            std::cout << "Invalid heading, can only be between 0 and 360 degrees" << std::endl;
        }
    }

#

//Heading can only be between 0-360?
    if (heading >= 0 && heading <= 360)
    {
        heading_ = heading;
    }
    else
    {
        std::cout << "Incorrect heading, heading can only be between 0 and 360" << std::endl;
    }

Should i do this instead? Is it as accurate/reliable?

Answer 1

If you still want regex (though this is not optimal) you can use the following expression:

std::regex re{ "^[0-9]$|^[1-9][0-9]$|^[1-2][0-9][0-9]$|^3[0-5][0-9]$|^360$" };
std::string headings[5] = { "0","15","390","360","23883" };

for (int i = 0; i < 5; ++i)
    std::cout << "Heading " << headings[i] << " is " << (std::regex_match(headings[i], re) ? "valid" : "invalid") << std::endl;

First part matches 0-9, second part matches 10-99, third part matches 100-299, fourth part matches 300-359, last matches 360. Prints:

Heading 0 is valid
Heading 15 is valid
Heading 390 is invalid
Heading 360 is valid
Heading 23883 is invalid