Return first digit of an integer

Question

How in Java do you return the first digit of an integer.?

i.e.

345

Returns an int of 3.

Answer 1

This is Groovy, but it should be easy to convert to Java:

int firstNum(int x) {
    a = Math.abs(x)
    sig = Math.floor(Math.log10(a))
    return a / Math.pow(10, sig)
}

Results:

groovy> println(firstNum(345))
3

groovy> println(firstNum(3452))
3

groovy> println(firstNum(-112))
1

groovy> println(firstNum(9999))
9

groovy> println(firstNum(Integer.MAX_VALUE))
2

groovy> println(firstNum(Integer.MIN_VALUE + 1))
2

Answer 2

//Try this one.
Scanner input = new Scanner(System.in);
System.out.println("enter first 9 digits: ");
String x = input.nextLine();
String x1 = x.substring(0,1);
int d1 = Integer.parseInt(x1);
System.out.println(d1);
// the substring gives the position of extraction. method dont seem to work for letters though

Answer 3

Looking at the code supplied it seems a tad over complicating the whole thing, here is a simple solution...

int number = 4085;
int firstDigit = number;
while (firstDigit > 9)
{
      firstDigit = firstDigit / 10;
}
System.out.println("The First Digit is " + firstDigit);

Answer 4

Homework Hint: Convert it to a string and and return the first character.

Answer 5

Here is a smaller version to get digits of all positions, it works with negative value (not decimal).

int number = -23456;

int length = (int) Math.log10(Math.abs(number)) + 1; //This gets the length of the number of digits used
//Math.abs to change negative int to positive

System.out.println("Digit at pos " + 1 + " is :- " + (int)(Math.abs(number)/Math.pow(10,(length-1))));

for (int i = 2; i <= length; i++){
    System.out.println("Digit at pos " + i + " is :- " + (int)(Math.abs(number)/Math.pow(10,(length-i))%10));
}

Answer 6

I think more simple to do :

int firstDigit = i-(i/10)*10 // i is an integer or long value, positive or negative.