为什么在将数字转换为整数的前面得到“ 0”？

Question

Example: when you type "1234567", it`s display "0 1 2 3 4 5 6 7". How can I rid of "0" in front part?

public static void main(String[] args){

    int num = 0;
    int eachNum = 0;
    Scanner input = new Scanner(System.in);

    System.out.print("Enter your number here: ");
    num = input.nextInt();

    int num2 =  num;
    int length = String.valueOf(num).length();
    while ( length >= 0 ) {

        int substraction =(int) Math.pow(10, length);
        int sub = (int) substraction; 
            eachNum = num2 / sub % 10;
            System.out.print(eachNum + "\t");
            length--;

    }

}//end main method

Answer 1

You could solve this by doing:

while (length > 0) { // iterating one less time
    int substraction = (int) Math.pow(10, length-1); // length-1 to get from first digit
    ...
}

Anyway you can improve your code and do little trick even, so you don't need the calculations:

Scanner input = new Scanner(System.in);
System.out.print("Enter your number here: ");    
int num = input.nextInt();  

String str = String.valueOf(num);
for (int i = 0; i < str.length(); i++) {
    System.out.print(str.charAt(i)+"\t");
}

Answer 2

Consider the first iteration.

length is 7 .

pow(10, 7) is 10,000,000 (I've put commas in for clarity).

num2 / sub % 10; is evaluated as (num2 / sub) % 10 due to the precedence of / and % being the same so evaluation is from left to right.

This is (1,234,567 / 10,000,000) % 10 which is 0 % 10 since integer division truncates the number. So your first output is 0 .

The simplest fix is probably to subtract 1 from the initial value of length .

Answer 3

Try this code. Now you will find your desire output

public static void main(String[] args){

    int num = 0;
    int eachNum = 0;
    Scanner input = new Scanner(System.in);

    System.out.print("Enter your number here: ");
    num = input.nextInt();

    int num2 =  num;
    int length = String.valueOf(num).length()-1;
    while ( length >= 0 ) {

        int substraction =(int) Math.pow(10, length);
        int sub = (int) substraction; 
            eachNum = (num2 / sub) % 10;
            System.out.print(eachNum + "\t");
            length--;

    }

}//end main

Answer 4

You should also skip case when num2 < substraction. I try changing while in this way:

while ( length >= 0 ) {
    int substraction =(int) Math.pow(10, length--);
    int sub = (int) substraction; 

    if (num2 < substraction)
        continue;

    eachNum = num2 / sub % 10;
    System.out.print(eachNum + "\t");
}