Question
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.
Solution
printf("%05d", zipCode);
OTHER TIPS
The correct solution is to store the zip code 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 zip code is not that.
You place a zero before the minimum field width:
printf("%05d",zipcode);
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);
).
If you are on a *NIX Machine:
man 3 printf
This will show a manual page, similar to:
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.
Even though the question is for C, this page may be of aid.
sprintf(mystring, "%05d", myInt);
Here, "05" says "use 5 digits with leading zeros".
printf allows various formatting options.
ex:
printf("leading zeros %05d", 123);
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.
More flexible.. Here's an example printing rows of right-justified numbers with fixed widths, and space-padding.
//---- Header
std::string getFmt ( int wid, long val )
{
char buf[64];
sprintf ( buf, "% *ld", wid, val );
return buf;
}
#define FMT (getFmt(8,x).c_str())
//---- Put to use
printf ( " COUNT USED FREE\n" );
printf ( "A: %s %s %s\n", FMT(C[0]), FMT(U[0]), FMT(F[0]) );
printf ( "B: %s %s %s\n", FMT(C[1]), FMT(U[1]), FMT(F[1]) );
printf ( "C: %s %s %s\n", FMT(C[2]), FMT(U[2]), FMT(F[2]) );
//-------- Output
COUNT USED FREE
A: 354 148523 3283
B: 54138259 12392759 200391
C: 91239 3281 61423
The function and macro are designed so the printfs are more readable.
If you need to store the zipcode in a character array zipcode[] , you can use this:
snprintf( zipcode, 6, "%05.5d", atoi(zipcode));