The use and distinction of the Linux Sleep () and usleep () __linux

Function Name: Sleep
Header file: #include <windows.h>//use with top files in VC
#include <unistd.h>//In the GCC compiler, the header file used differs depending on the version of GCC
Function: Execution suspend specified number of seconds
Grammar: Unsigned sleep (unsigned seconds);


Example:
#include <windows.h>
#include <stdio.h>
int main ()
{
int A;
A=1;
printf ("Hello");
Sleep (a); * VC Use sleep*/
printf ("World");
return 0;
}


Function Name: Usleep
Header files: #include <unistd.h>
Function: Usleep function to suspend the process for a period of time, the Unit is microsecond (one out of 10,000 seconds);
Syntax: void usleep (int micro_seconds);
return value: None
Content Description: This function can temporarily stop the execution of the program. The parameter micro_seconds is the number of microseconds (US) to pause.
Attention
This function does not work in the Windows operating system. Used under the Linux test environment.
See also: Usleep () is similar to sleep () for delaying a pending process. The process is suspended and placed in the Reday queue.
In general, the Sleep () function is used whenever possible when the order of magnitude of delay is seconds.
If the delay time is dozens of milliseconds (1ms = 1000us), or smaller, use the usleep () function whenever possible. This will make the best use of CPU time




Clock conversion:
microsecond, time unit, symbol US (English: microsecond).
1 microseconds equals one out of 10,000 seconds (10 minus 6 second square seconds)
0.000 001 microseconds = 1 picosecond
0.001 microseconds = 1 nanoseconds
1,000 microseconds = 1 milliseconds
1,000,000 microseconds = 1 seconds
1s = 1000ms
1ms = 1000μs
1μs = 1000ns
1ns = 1000ps
1 seconds (s) = 1000 ms (ms) = 1,000,000 microseconds (μs) = 1,000,000,000 nanoseconds (ns) = 1,000,000,000,000 picosecond (PS)