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FirstAndLastDigitSum.java
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FirstAndLastDigitSum.java
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// Write a method named sumFirstAndLastDigit with one parameter of type int called number.
// The method needs to find the first and the last digit of the parameter number passed to the method, using a loop and return the sum of the first and the last digit of that number.
// If the number is negative then the method needs to return -1 to indicate an invalid value.
// Example input/output
// sumFirstAndLastDigit(252); → should return 4, the first digit is 2 and the last is 2 which gives us 2+2 and the sum is 4.
// sumFirstAndLastDigit(257); → should return 9, the first digit is 2 and the last is 7 which gives us 2+7 and the sum is 9.
// sumFirstAndLastDigit(0); → should return 0, the first digit and the last digit is 0 since we only have 1 digit, which gives us 0+0 and the sum is 0.
// sumFirstAndLastDigit(5); → should return 10, the first digit and the last digit is 5 since we only have 1 digit, which gives us 5+5 and the sum is 10.
// sumFirstAndLastDigit(-10); → should return -1, since the parameter is negative and needs to be positive.
public class FirstAndLastDigitSum
{
public static int sumFirstAndLastDigit (int num)
{
if (num < 0)
return -1;
int first = 0, last = num % 10;
num = num / 10;
while (num != 0)
{
if (num / 10 == 0)
first = num % 10;
num = num / 10;
}
return first + last;
}
public static void main (String[]args)
{
System.out.println (sumFirstAndLastDigit (352));
System.out.println (sumFirstAndLastDigit (1));
System.out.println (sumFirstAndLastDigit (-7));
}
}