C++ 中的日期验证和转换

Question

I have to write 2 functions. One that takes in a date as a string and checks if its in mm/dd/yy format; if its not in the correct format, it should be edited to make it so. The other function should convert the validated date to the format "Month dd, 20yy".

I'm pretty sure I can take care of the second function, but I am having trouble with the first one. I just have no idea how to check if its in that format... any ideas?

I thought that this would work, but it doesn't seem to...

Updated code:

bool dateValidation(string shipDate)
{
    string temp;
    if(shipDate.length() == 8 )
    {
        if(shipDate[2] == '/' && shipDate[5] =='/')
        {
            int tempDay, tempMonth, tempYear;
            //Gather month
            temp = shipDate[0];
            temp += shipDate[1];
            //convert string to int
            tempMonth = temp.atoi;
            temp = "";

            //Gather day
            temp = shipDate[3];
            temp += shipDate[4];
            //convert string to int
            tempDay = temp.atoi;
            temp = "";

            //Gather year
            temp = shipDate[6];
            temp += shipDate[7];
            //convert string to int
            tempYear = temp.atoi;
            temp = "";

            if(tempMonth > 0 && tempMonth <= 12)
            {

                if(tempMonth == 9 ||
                   tempMonth == 4 ||
                   tempMonth == 6 ||
                   tempMonth == 11 ||)
                {
                    if(tempDay > 0 && tempDay <= 30)
                    {
                        if 30 days
                            }
                }
                else if(tempMonth == 2)
                {
                    if(tempDay > 0 && tempDay <= 28)
                    {
                        if 28 days
                            }
                }
                else
                {
                    if(tempDay > 0 && tempDay <= 31)
                    {
                        if 31 days
                            }
                }
            }
        }
    }
}

Answer 1

There are 4 things you want to check:

• Is there 8 characters ? If not, then don't even bother checking anything else. It's not in the proper format.
• Are the third and fifth characters '/'. If not, then you still don't have the proper format.
• Check each pair for its valid values. A month has days between 1 and 31 at most, there are no more than 12 months and months range from 01 to 12. A year can be any combination of any 2 digits.

This should take care of the format, but if you want to make sure that the date is valid:

• Check for valid number of days in each month (january 31, february 28-29...) and indeed check for those leap years.

Answer 2

This looks a lot like a project I am about to grade.... You should verify that it is Gregorian Calendar compliant if it is the project I am about to grade. 1/1/2012 is definitely valid though so what you may want to do and what I would hope you consider is creating a switch statement that examines for formats like 1/12/2012 and 10/2/2012 because these are valid. Then parse out the month day and year from these. Then verify that they are within the limit of the Gregorian calendar. If it is for a class which I would guess that it is, you should consider writing the verification as a separate function from the parsing function.

So first ask whether the date is too long if not, is it too short, if not which version is it, then pass the dmy to the verification function. This kind of modularity will simplify your code and reduce instructions.

something like

bool dateValidation(string shipDate) { string temp;

switch(shipDate.length())
{
     case(10):
        // do what  your doing
        verify(m,d,y);
        break;

     case(8):
        //dealing with single digits
        // verify 1 and 3 are '/' and the rest are numbers
        verifiy(m,d,y);
        break;

     case(9):
        //a little more heavy lifting here 
        // but its good thinking for a new programmer
        verifiy(m,d,y);
        break;
     default:       

      //fail message
        break;
}