How can I include leading zeros in a number?

I've created a code that requires the user to input a number of their choice. Their number must follow a set of rules, the first being that it must be 6 digits otherwise an error message occurs.

If the user types a number such as 012345, MatLab discards the zero and counts it as a 5 digit number (12345). If I would like MatLab to understand that this is actually a 6-digit number, how would i go about that?

Answer 1

[Cedric]

Store/read the user input as a string.

Or, if you want to bring some flexibility, allow users to enter integers without leading zeros, but then when it becomes important to use/display them with leading zeros, print them on 6 digits with a 0 padding:

 n           = 12 ;                     % Stored or entered by user.
 n_strPadded = sprintf( '%06d', n ) ;

with that you get:

 n_strPadded =
    '000012'

[RAHUL SAINI]

here we get n_strPadded = '000012' but I want to know how to get n_strPadded = 000012

[Jan]

@RAHUL: The question is not meaningful. There is not object like 00012. If the number 12 is meant, there are no leading zeros. You can add leading zeros only, if you represent 12 as a string. If you display this string, the quotes are not printed. Try it:

n = 12;
fprintf('%06d', n)

[Real User]

Great except that it counts the minus sign as one "zero". Thus, sprintf('%06d', n) works if n>=0 but sprintf('%07d', n) if n<0. Is there any way to say that I want 6 numbers whether n<0 or not?

[Stephen23]

"Is there any way to say that I want 6 numbers whether n<0 or not?"

I guess you mean digits, not numbers. Here are two approaches:

n = +4;
sprintf('%0*d',(n<0)+6,n)

ans = '000004'

n = -4;
sprintf('%0*d',(n<0)+6,n)

ans = '-000004'

OR

n = +4;
sprintf('%+07d',n)

ans = '+000004'

n = -4;
sprintf('%+07d',n)

ans = '-000004'

Answer 2

[Walter Roberson]

Use input with the 's' option, and test for length() 6 and that it contains only digits.