Question

I’ve searched high and low, but in printf in C it seems that there’s only zero fill and white space fill. I’m looking to write my own fill, in this case using the asterisk.

For example,

Assuming a width of 8 character.

Input: 123
Ouput: **123.00

Input: 3
Output: ****3.00

How can I do that?

Answer 1

The simplest way is probably to print into a buffer using snprintf() with space padding, then replace the spaces with asterisks afterwards:

void print_padded(double n)
{
    char buffer[9];
    char *p;

    snprintf(buffer, sizeof buffer, "% 8.2f", n);
    for (p = buffer; *p == ' '; p++)
        *p = '*';
    printf("%s", buffer);
}