I'm trying to find a good way to print leading 0's, such as 01001 for a zipcode. While the number would be stored as 1001, what is a good way to do it?
I thought of using either case statements/if then to figure out how many digits the number is and then convert it to an char array with extra 0's for printing but I can't help but think there may be a way to do this with the printf format syntax that is eluding me.
printf allows various formatting options.
ex:
printf("leading zeros %05d", 123);
You place a zero before the minimum field width:
printf("%05d",zipcode);
man 3 printf
0 The value should be zero padded. For d, i, o, u, x, X, a, A, e, E, f, F, g, and G conversions, the converted value is padded on the left with zeros rather than blanks. If the 0 and - flags both appear, the 0 flag is ignored. If a precision is given with a numeric conversion (d, i, o, u, x, and X), the 0 flag is ignored. For other conversions, the behavior is undefined.
sprintf(mystring, "%05d", myInt);
"05" says use 5 digits, with leading zeros.
The correct solution is : Store the Zipcode in the database as a STRING. Despite the fact that it may look like a number, it isn't. It's a code, where each part has meaning.
A number is a thing you do arithmetic on. A zipcode is not that.
Zipcode is a highly localised field, many countries have characters in their postcodes, e.g., UK, Canada. Therefore in this example you should use a string / varchar field to store it if at any point you would be shipping or getting users/customers/clients/etc from other countries.
However in the general case you should use the recommended answer (printf("%05d", number);).
You will save yourself a heap of trouble (long term) if you store a zip code as a character string, which it is, rather than a number, which it is not.