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This is quite a beginner question but I'm wondering why my do...while loop is not closing.
The program is supposed to loop while the user input is not 'C', 'c', 'F', or 'f'.
It seems to close when just one boolean expression in the while section is valid but not if multiple are valid.
public class CelsToFaren
{
public static void main(String[] args)
{
// scanner setup
Scanner sc = new Scanner(System.in);
// Variable declarations
int celsius;
int answerC;
int farenheit;
int answerF;
char userLetter;
do
{
// initial menu options
System.out.println("Which temperature would you like to convert from? ");
System.out.println(" >(C)elsius ");
System.out.println(" >(F)arenheit ");
// user input of C, c, F, or f to select option
userLetter = sc.next().charAt(0);
// if user input C or c
if ((userLetter == 'C' || userLetter == 'c'))
{
System.out.print("Please enter the temperature: ");
celsius = sc.nextInt();
answerC = ((celsius*9/5)+32);
System.out.println("The answer is: " + answerC + " Farenheit ");
}
else
{
// if user input F or f
if ((userLetter == 'F' || userLetter == 'f'))
{
System.out.print("Please enter the temperature: ");
farenheit = sc.nextInt();
answerF = ((farenheit-32)*5/9);
System.out.println("The answer is: " + answerF + " Celsius ");
}
else
{
// if user input not F, f, C, or c
if ((userLetter != 'F' || userLetter != 'f' || userLetter != 'C' || userLetter != 'c'));
{
System.out.println("Please enter a valid option");
}
}
}
} while ((userLetter != 'c') || (userLetter != 'C') || (userLetter != 'f') || (userLetter != 'F'));
}
}
528
The do-while loop executes a block of code while a boolean expression evaluates to true. It checks the boolean expression after each iteration. It terminates as soon as the expression evaluates to false.
You need to use while (result != 1 && result != 0) . This will loop only if the answer is both not equals to 1 and not equals to 0.
If you check inside the loop then it will not work it will still multiply the fact . You need to make sure that the num is not negative before you start the while loop. int num = 0; do { if (num<0){ System.
You need to change the exit logic.
In your case 1 | 0 | 0 = true so the loop continues.
You need to change it to:
while ((userLetter != 'c') && (userLetter != 'C') && (userLetter != 'f') && (userLetter != 'F'));
Your condition is wrong. Lets assume you want to break loop in if statement. It would look like
if(userLetter == 'c' || userLetter == 'C' || userLetter == 'f' || userLetter == 'F')
Now let's apply negation to get a condition under which you do not need to exit the loop
if(!(userLetter == 'c' || userLetter == 'C' || userLetter == 'f' || userLetter == 'F'))
this condition is simillar to
if(userLetter != 'c' && userLetter != 'C' && userLetter != 'f' && userLetter != 'F')
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