Display time string given system tick count

Question

Given:

• number of system ticks since cold start via unsigned int systemTicks(void);
• number of microseconds per system tick via unsigned int usPerTick(void);

How can I create a fixed-width time stamp string in C? I can be flexible in this format, but would like to support a maximum of 100 minutes and keep millisecond resolution. One example format would be "99:59:999" meaning it has been 99 mins and 59.999 seconds since cold start.

printf allows me to write decimals (minute, second, ms) with a minimum width, but not a maximum width. I am looking for simple solutions.

Answer 1

You want to print a fixed width, leading zeroes fractional part for the microseconds. Since there are 6 digits in microseconds, you want,

sprintf(timestamp,"%d:%02d.%06d",ticks/60,ticks%60,mseconds);

And add struct/pointer flavor to taste...