Converting a time in string format to minutes

[ae_jester]

I'm using C++ Builder 6

I'm trying to convert a string in the form "12:25", which represents a time of day, to minutes. So in this case "12:25" would become 745.

I've never done anything like this, and I can't seem to get anything working. I'm sure its something extremely simple.

I also need to convert a time in minutes to a time string, so 745 minutes would return "12:25", but I will attemp to do this part myself provided someone can assist me with the first part.

Thanx for any help!

[HairyDave]

I don't know if there's an easier way, but couldn't you:

1. Tokenise the string (using strtok or other) to be an hours string and a minutes string.
2. Convert both to integers (atoi or other).
3. ( hours * 60 ) + minutes = total

Is that what you're looking for - or were you looking for something at a higher level?

HD

[parksie]

If you know it's only going to be in the form "hh:mm" (including leading zeros, and 24-hour clock), you can do this:

inline char down(char c) { return c - '0'; }

// ...

string dt = "23:12";

int minutes = down(dt[0]) * 10 * 60;
minutes += down(dt[1]) * 60;
minutes += down(dt[3]) * 10;
minutes += down(dt[4]);

...or similar. I wouldn't *really* recommend that, since it has no error checking whatsoever. I'll leave that as an exercise for the reader

[kedaman]

or maybe something like this

int minutes = (dt[0]*10+dt[1])*60+dt[3]*10+dt[4]-0x7DD0;

[parksie]

Heh. You win

[CornedBee]

Other way round is even easier:
C:

void minstotime(int mins, char *buffer) {
  sprintf(buffer, "%02i:%02i", mins/60, mins%60);
}

C++:

void minstotime(int mins, string &str) {
  ostringstream oss;
  oss << setw(2) << setfill('0') << mins/60;
  oss << ':';
  oss << setw(2) << setfill('0') << mins%60;
  str = oss.str();
}