padding with sprintf

You got the syntax slightly wrong; The following code produces the desired output:

char buf[31];
int my_val = 324;
sprintf( buf, "%030d", (int)my_val );

From Wikipedia's Article on Printf:

[...] printf("%2d", 3) results in " 3", while printf("%02d", 3) results in "03".

The padding and width come before the type specifier:

sprintf( buf, "%030d", my_val );

"%030d" is the droid you are looking for

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