Variable sized padding in printf

Question

Is there a way to have a variable sized padding in printf?

I have an integer which says how large the padding is:

void foo(int paddingSize) {     printf("%...MyText", paddingSize); } 

This should print out ### MyText where the paddingSize should decide the number of '#' symbols.

Answer 1

Yes, if you use * in your format string, it gets a number from the arguments:

printf ("%0*d\n", 3, 5); 

will print "005".

Keep in mind you can only pad with spaces or zeros. If you want to pad with something else, you can use something like:

#include <stdio.h> #include <string.h> int main (void) {     char *s = "MyText";     unsigned int sz = 9;     char *pad = "########################################";     printf ("%.*s%s\n", (sz < strlen(s)) ? 0 : sz - strlen(s), pad, s); } 

This outputs ###MyText when sz is 9, or MyText when sz is 2 (no padding but no truncation). You may want to add a check for pad being too short.