How to Count Integers With Padded Zeros

user_16489668 0
Viewed 33

I want to count from 1 to 10 with a variable width.

Example for width: 4

Count Should Be:

0001 0002 0003 0004 0005 0006 0007 0008 0009 0010 ---> Note that it's not 00010

Example for width: 2

Count Should Be:

01 ... 09 10 ---> Not 010

I've tried the following:

First attempt

for(int i = 1; i <= 10; ++i) {
   System.out.println("0".repeat(width-1) + i);
}

Second attempt

String output = String.format("%04d", 1);

These do not properly format numbers as the number of digits changes.

output format java string
2 Answers

A more flexible approach will be to provide width, start and end the sequence dynamically, so that none of the values will be hard coded.

A template for the output with the given width will be created by using string concatination.

public static void printZeroPaddedSequence(int start, int end, int width) {
    String template = "%0" + width + "d ";
    for (int i = start; i <= end; i++) {
        System.out.printf("template", i);
    }
}

public static void main(String[] args) {
    printZeroPaddedSequence(1, 10, 4);
}

Output

0001 0002 0003 0004 0005 0006 0007 0008 0009 0010
user_179499450

You can create a format String with a variable length of format specifier. Adjust the width variable to whatever leading 0s you need.

int width = 2;
String format = "%0"+width+"d";

for(int i = 1; i <= 10; i++)  {
    String output = String.format(format, i);
    System.out.println(output);
}


/* Output:
01
02
03
04
05
06
07
08
09
10
*/
user_20918030
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