Whats wrong with my “while” statement

Question

int monthentered = 0;
int dayentered = 0;
int year = 0000;
int [] month = new int [12];
int [] day = new int [31];
bool leap = false;

for (int x = 0; x <= 11; x++)
{
    month[x] = x+1;
}

for (int x = 0; x <= 30; x++)
{
    day[x] = x+1;
}
Console.WriteLine("Please enter a year...");
year = (Convert.ToInt16(Console.ReadLine()));
Console.WriteLine("{0}", year);

Console.WriteLine("Please enter a month...");
monthentered = (Convert.ToInt16(Console.ReadLine()));

Console.WriteLine("Please enter a day...");
dayentered = (Convert.ToInt16(Console.ReadLine()));

while (monthentered == 01 || 03 || 05 || 07 || 08 || 10 || 12)
{
    while (dayentered == 31)
    {
        Console.WriteLine("There are only 30 days in this month please re-enter your day...");
        dayentered = (Convert.ToInt16(Console.ReadLine()));
    }
}

while (monthentered == 02)
{
    while (dayentered > 28)
    {
        Console.WriteLine("There are only 28 days in this month please re-enter your day...");
        dayentered = (Convert.ToInt16(Console.ReadLine()));
    }
}

Console.WriteLine("{0}/{1}/{2}", dayentered, monthentered, year);
Console.ReadKey();

Is there anything wrong with line while (monthentered == 01 || 03 || 05 || 07 || 08 || 10 || 12) ? I getting an error that I don't understand. "Operator '||' cannot be applied to operands of type 'bool' and 'int'"

Please help.

Answer 1

while(monthentered == 01 || monthentered == 03 || monthentered == 05 || monthentered == 07 || monthentered == 08 || monthentered == 10 || monthentered == 12)

Every operation between || and && have to render to a boolean value (ie a complete test) since every operation is independently calculated

Answer 2

Now it is something like while(bool || int || int) , I guess that you want something like this:

while (monthentered == 1 || monthentered == 3 || monthentered == 5 /*|| ...*/)

You need to check value of variable every time so it will be while(bool || bool || bool) etc

You can also create collection of valid months and check wheter entered number is in it.

Answer 3

Operator '||' cannot be applied to operands of type 'bool' and 'int'

You can't use || on numbers - each part you are using || with should evaluate to a bool .

The conditional should look like:

while (monthentered == 01 || 
       monthentered == 03 || 
       monthentered == 05 || 
       monthentered == 07 || 
       monthentered == 08 || 
       monthentered == 10 || 
       monthentered == 12)

Though a more readable option would be:

var validMonths = new int[] { 1, 3, 5, 7, 8, 10, 12 };

while(validMonths.Contains(monthentered))

Answer 4

它应该是

while (monthentered  == 01 ||monthentered  == 03 || monthentered  ==05 || monthentered  ==07 || monthentered  ==08 || monthentered  ==10 || monthentered  ==12)

Answer 5

You cannot compare an int with a bool with || operator . monthentered == 01 is a bool (true/false) and the rest are ints .

So change the while to:

int[] allAllowedMonths = new[]{ 1, 3, 5, 7, 8, 10, 12 };
while (allAllowedMonths.Contains( monthentered ))
{
    // ...
}

Answer 6

C＃同时仅接受true / false表达式！

while (monthentered == 01 || monthentered ==03 || monthentered ==05 || monthentered ==07 || monthentered ==08 || monthentered ==10 || monthentered ==12) 

Answer 7

it should be

while (monthentered == 01 || 
       monthentered == 03 || 
       monthentered == 05 || 
       monthentered == 07 || 
       monthentered == 08 || 
       monthentered == 10 || 
       monthentered == 12)

 {  
   //code here
 }

Answer 8

Direct answer that leads to code that compiles but won't work : you need to use

(monthentered == 01 || monthentered == 03 || monthentered == 05 ||
 monthentered == 07 || monthentered == 08 || monthentered == 10 ||
 monthentered == 12)

Further issues:

• your code allows 32+ days in most months.
• your while loops on months will never terminate, as you never change the value of the month. Use an if statement instead.

Extra hint: you can use DateTime.DaysInMonth to get the maximum number to allow for each month and year, rather than manually checking the month number. This will also accommodate leap years.

Answer 9

It's tedious syntax but you would need to write the while statement as:

while (monthentered == 01 || monthentered == 02 || monthentered == 3 ...etc

Your statement will first evaluate the boolean condition monthentered == 01 and then try to logically or the result with the other numbers which are ints hence the error.

However I'd take a look at what you're trying to do and see if a while loop is really what you want here.