Add leading zero's to string, without (s)printf

Question

I want to add a variable of leading zero\'s to a string. I couldn\'t find anything on Google, without someone mentioning (s)printf, but I want to do this without (s)printf.<

Answer 1

memcpy(target,'0',sizeof(target));
target[sizeof(target)-1] = 0;

Then stick whatever string you want zero prefixed at the end of the buffer.

If it is an integer number, remember log_base10(number)+1 (aka ln(number)/ln(10)+1) gives you the length of the number.