Explanation and Implementation of usleep and nanosleep Functions in C Language for Millisecond-Level Sleep.

2 years ago
Benjamin Taylor
2 minutes

In C language, both the usleep and nanosleep functions are used to implement the program’s sleep functionality.

  1. The usleep function is used to pause the execution of a program for a specified amount of time, measured in microseconds. It takes a parameter in microseconds to indicate the duration of the pause. The function prototype is as follows:
  2. Include the unistd header and define a function that pauses the program for a specified number of microseconds.
  3. useconds_t is an unsigned integer type used to represent microseconds. The function returns 0 upon successful call and -1 upon failure.
  4. The nanosleep function is used to pause the execution of a program for a specified amount of time. It takes a parameter in nanoseconds to determine the duration of the pause. The function prototype is as follows:
  5. The “time.h” library is included in order to use the function “nanosleep”, which pauses the program for the specified amount of time in nanoseconds.
  6. The req parameter is a pointer to a struct, used to specify the length of time to sleep, with the timespec struct defined as follows:
  7. The struct timespec contains two elements: tv_sec for seconds and tv_nsec for nanoseconds.
  8. The rem parameter is a pointer to a structure used to store the remaining sleep time. The function returns 0 if successful and -1 if unsuccessful.

To achieve millisecond-level sleep, you can use the usleep function. Since the usleep function accepts parameters in microseconds, you can convert milliseconds to microseconds and pass it to the usleep function. For example, to sleep for 100 milliseconds, you can use the following code:

#include <unistd.h>

void sleep_ms(unsigned int milliseconds) {
    usleep(milliseconds * 1000);
}

The function sleep_ms in the code takes a parameter in milliseconds, converts it to microseconds, and passes it to the usleep function, allowing for millisecond-level sleep.

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