Including Zeros in Front of an Integer

Including zeros in front of an integer

The literal 000000000 means the same thing as 0 to the compiler.

You can use stringWithFormat: to add leading zeros when converting to a string (assuming you have import Foundation):

String(format: "%09ld", score)

What does an integer that has zero in front of it mean and how can I print it?

The JLS 3.10.1 describes 4 ways to define integers.

An integer literal may be expressed in decimal (base 10), hexadecimal (base 16), octal (base 8), or binary (base 2).

An octal numeral consists of a digit 0 followed by one or more of the digits 0 through 7 ...

A decimal numeral is either the single digit 0, representing the integer zero, or consists of an digit from 1 to 9 optionally followed by one or more digits from 0 to 9 ...

In summary if your integer literal (i.e. 011) starts with a 0, then java will assume it's an octal notation.

octal conversion example

Solutions:

If you want your integer to hold the value 11, then don't be fancy, just assign 11. After all, the notation doesn't change anything to the value. I mean, from a mathematical point of view 11 = 011 = 11,0.

int a = 11;

The formatting only matters when you print it (or when you convert your int to a String).

String with3digits = String.format("%03d", a);
System.out.println(with3digits);

The formatter "%03d" is used to add leading zeroes.

formatter

Alternatively, you could do it in 1 line, using the printf method.

System.out.printf("%03d", a);

How do I retain leading zeroes in an Integer/Number in JavaScript?

You can't have a number with leading zeroes in Javascript, because, as Randy Casburn said, they don't have any value. You have to convert it to a string and use String.padStart() to pad the string with zeroes. parseInt will work with leading zeroes. For example:

(294).toString().padStart(6, "0") --> "000294"

parseInt("000294") --> 294

Is it possible to store a leading zero in an int?

An int basically stores leading zeros. The problem that you are running into is that you are not printing the leading zeros that are there.

Another, different approach is to create a function that will accept the four int values along with a string and to then return a string with the numbers.

With this approach you have a helper function with very good cohesion, no side effects, reusable where you need something similar to be done.

For instance:

char *joinedIntString (char *pBuff, int int1, int int2, int int3, int int4)
{
pBuff[0] = (int1 % 10) + '0';
pBuff[1] = (int2 % 10) + '0';
pBuff[2] = (int3 % 10) + '0';
pBuff[3] = (int4 % 10) + '0';
pBuff[4] = 0; // end of string needed.
return pBuff;
}

Then in the place where you need to print the value you can just call the function with the arguments and the provided character buffer and then just print the character buffer.

With this approach if you have some unreasonable numbers that end up have more than one leading zero, you will get all of the zeros.

Or you may want to have a function that combines the four ints into a single int and then another function that will print the combined int with leading zeros.

int createJoinedInt (int int1, int int2, int int3, int int4)
{
return (int1 % 10) * 1000 + (int2 % 10) * 100 + (int 3 % 10) * 10 + (int4 % 10);
}

char *joinedIntString (char *pBuff, int joinedInt)
{
pBuff[0] = ((joinedInt / 1000) % 10) + '0';
pBuff[1] = ((joinedInt / 100) % 10) + '0';
pBuff[2] = ((joinedInt / 10) % 10) + '0';
pBuff[3] = (joinedInt % 10) + '0';
pBuff[4] = 0; // end of string needed.
return pBuff;
}

Printing leading zeros in a number in C

The best way to have input under control is to read in a string and then parse/analyze the string as desired. If, for example, "exactly five digits" means: "exactly 5 digits (not less, not more), no other leading characters other than '0', and no negative numbers", then you could use function strtol, which tells you where number parsing has ended. Therefrom, you can derive how many digits the input actually has:

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>

int main() {

char line[50];
if (fgets(line,50,stdin)) {
if (isdigit((unsigned char)line[0])) {
char* endptr = line;
long number = strtol(line, &endptr, 10);
int nrOfDigitsRead = (int)(endptr - line);
if (nrOfDigitsRead != 5) {
printf ("invalid number of digits, i.e. %d digits (but should be 5).\n", nrOfDigitsRead);
} else {
printf("number: %05lu\n", number);
}
}
else {
printf ("input does not start with a digit.\n");
}
}
}

How does C Handle Integer Literals with Leading Zeros, and What About atoi?

Leading zeros indicate that the number is expressed in octal, or base 8; thus, 010 = 8. Adding additional leading zeros has no effect; just as you would expect in math, x + 0*8^n = x; there's no change to the value by making its representation longer.

One place you often see this is in UNIX file modes; 0755 actually means 7*8^2+5*8+5 = 493; or with umasks such as 0022 = 2*8+2 = 10.

atoi(nptr) is defined as equivalent to strtol(nptr, (char **) NULL, 10), except that it does not detect errors - as such, atoi() always uses decimal (and thus ignores leading zeros). strtol(nptr, anything, 0) does the following:

The string may begin with an arbitrary
amount of white space (as determined
by isspace(3)) followed by a single
optional '+' or '-' sign. If base is
zero or 16, the string may then
include a "0x" prefix, and the number
will be read in base 16; otherwise, a
zero base is taken as 10 (decimal)
unless the next character is '0', in
which case it is taken as 8 (octal).

So it uses the same rules as the C compiler.

Put zeros in front of a number to make it 4 digits

Several Pythonic ways to do this, I am really liking the new f-strings as of Python 3.6:

>>> f'{5:04}'
'0005'

This uses the string formatting minilanguage:

>>> five = 5
>>> f'{five:04}'
'0005'

The first zero means the fill, the 4 means to which width:

>>> minimum_width = 4
>>> filler = "0" # could also be just 0
>>> f'{five:{filler}{minimum_width}}'
'0005'

Next using the builtin format function:

>>> format(5, "04")
'0005'
>>> format(55, "04")
'0055'
>>> format(355, "04")
'0355'

Also, the string format method with the minilanguage:

>>> '{0:04}'.format(5)
'0005'

Again, the specification comes after the :, and the 0 means fill with zeros and the 4 means a width of four.

Finally, the str.zfill method is custom made for this, and probably the fastest way to do it:

>>> str(5).zfill(4)
'0005'


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