C++ number formating help

kaylachris · 02-11-2011, 03:36 AM

I have the following code that complies and executes just fine. However, its been some time since I've dealt with C++ and need to format the output a little better.

Code:

#include <iostream>  
#include <fstream>  
#include <math.h>  
#include <unistd.h>  
using namespace std;  

void work(void)  
 {  
 double y;  
 double x = 3.0;  
 double e = 2.0;  
 int i,j;  

 for(i=0; i<5; i++)  
 {  
   for(j=0; j<400000; j++)  
   {  
     y=pow(x,e);  
   }  
   printf("Loop %d of work cycle\n", i);  
  //pause for one second between loops so that the work cycle takes a little time.  
   sleep(1); 
 }  
}  
    
int main(void)  
{  
 double beginTotalTime;  
 double beginIdleTime;  
 double endTotalTime;  
 double endIdleTime;  
 double programTotalTime = 0.0;  
 double programIdleTime = 0.0;  
 double programWorkTime = 0.0;  
 double percentage = 0.0;  

 ifstream out("/proc/uptime");  
 out >> beginTotalTime >> beginIdleTime;  
 out.close();
 work();  
 out >> endTotalTime >> endIdleTime;  
 out.close();  

 cout << "beginTotalTime: " << beginTotalTime << " beginIdleTime: " << beginIdleTime <<endl;
 cout << "  endTotalTime: " << endTotalTime << "   endIdleTime: " <<endIdleTime << endl;

 //Perform calculations
 programTotalTime = beginTotalTime - endTotalTime;  
 programIdleTime = beginIdleTime - endIdleTime;  
 programWorkTime = programTotalTime - programIdleTime;  
 percentage = (programWorkTime/programTotalTime) * 100;  

 //Print results
 cout << "\nThe program's Total Time is:   " << programTotalTime << endl;  
 cout << "The program's Idle Time is:    " << programIdleTime << endl;  
 cout << "The program's Work Time is:    " << programWorkTime << endl;  
 cout << "The percentage the CPU was busy: " << percentage << "%" << endl;  

 return 0;  
}

With output of:

Quote:

Loop 0 of work cycle
Loop 1 of work cycle
Loop 2 of work cycle
Loop 3 of work cycle
Loop 4 of work cycle

beginTotalTime: 1.92928e+07 beginIdleTime: 2.08111e+06
endTotalTime: 1.92928E+07 endIdleTime: 2.08111e+06

The program's Total Time is: 5.23
The program's Idle Time is: 5.02
The program's Work Time is: 0.21
The percentage the CPU was busy: 4.0153%

my question is how do I format the beginTotalTime, etc into a more readable form? something along the lines of days, hours, mins, sec...
Any help would be appreciated.
thank you

goossen · 02-11-2011, 05:34 AM

dwhitney67 · 02-11-2011, 06:08 AM

You could consider setting the float-point precision on the cout object. For example:

Code:

...
#include <iomanip>

...

std::cout.precision(6);
std::cout << "beginTotalTime ...

...

Btw, after you close the file stream referencing /proc/uptime, don't you think that you should re-open the file to get fresh time readings for your end-times? Examine the code you posted; this step is missing. :-)

As for converting the system times in /proc/utime to something more readable, you may need to develop your own function to convert the seconds. Something like this:

Code:

#include <sstream>
...

std::string date(double time)
{
   double days, hours, minutes, seconds;

   days  = floorl(time / 86400.0);
   time -= (86400.0 * days);

   hours = floorl(time / 3600.0);
   time -= (3600.0 * hours);

   minutes = floorl(time / 60.0);
   time -= (60.0 * minutes);

   seconds = time;

   std::stringstream ss;
   ss << days << " days "
      << std::setw(2) << std::setfill('0')
      << hours << ":" << minutes << ":" << seconds;

   return ss.str();
}

...

std::cout << "beginTotalTime: " << date(beginTotalTime) << ...