Calculating Time Difference in Milliseconds with time.h

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SUMMARY

The discussion focuses on calculating time differences in milliseconds using the C standard library's time.h header. For Windows, the QueryPerformanceCounter() function is recommended for high-resolution timing, while PerformanceCounterFrequency() provides the tick frequency, approximately 10 MHz. For Linux, gettimeofday() is suggested as a suitable alternative, which returns time in microseconds since the start of the day. Users are encouraged to search for alternatives to QueryPerformanceCounter() for Linux systems.

PREREQUISITES
  • Understanding of C programming language
  • Familiarity with the time.h header file
  • Knowledge of Windows and Linux operating systems
  • Basic concepts of high-resolution timers
NEXT STEPS
  • Research the usage of QueryPerformanceCounter() and PerformanceCounterFrequency() in Windows
  • Explore the gettimeofday() function in Linux for time measurement
  • Investigate multimedia timers for high-resolution timing on Windows
  • Look for Linux alternatives to QueryPerformanceCounter() for precise timing
USEFUL FOR

Software developers, particularly those working with performance-critical applications in C, and anyone needing precise time measurements across different operating systems.

ehrenfest
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I have been using the time.h header and the difftime function is good if you want to know the difference between two events measured in seconds but how do you get the difference between two events that occur milliseconds apart?
 
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It depends on your operating system.
On windows QueryPerformanceCounter() will tell you the number of ticks since the last call, PerformanceCounterFrequency() tells you the frequency of the ticks ( it's about 10Mhz IIRC). Also take a look at 'multimedia timers'.
 
mgb_phys said:
It depends on your operating system.
On windows QueryPerformanceCounter() will tell you the number of ticks since the last call, PerformanceCounterFrequency() tells you the frequency of the ticks ( it's about 10Mhz IIRC). Also take a look at 'multimedia timers'.

I am using Linux.
 
gettimeofday() contains microseconds since start of day,
I don't know what frequency it is updated at.
But if you google for QueryPerformanceCounter() alternatives under linux you should find something.
 
mgb_phys said:
gettimeofday() contains microseconds since start of day,
I don't know what frequency it is updated at.
But if you google for QueryPerformanceCounter() alternatives under linux you should find something.

Yes, gettimeofday is a good alternative. Function details here: http://www.linuxmanpages.com/man2/gettimeofday.2.php
 
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