how to create files named with current time?

Question

I want to create a series of files under \"log\" directory which every file named based on execution time. And in each of these files, I want to store some log info for my p

Answer 1

What about this:

#include 
#include 

#define LOGNAME_FORMAT "log/%Y%m%d_%H%M%S"
#define LOGNAME_SIZE 20

FILE *logfile(void)
{
    static char name[LOGNAME_SIZE];
    time_t now = time(0);
    strftime(name, sizeof(name), LOGNAME_FORMAT, localtime(&now));
    return fopen(name, "ab");
}

You'd use it like this:

FILE *file = logfile();
// do logging
fclose(file);

Keep in mind that localtime() is not thread-safe!