Some time functions in C language (time/sleep/clock)

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Some time functions in C language (time/sleep/clock) [Copy link]

1.time function

Header file: #include <time.h> (I can still run it without adding this header file)
Define function: time_t time(time_t *t);
Function description: This function returns the number of seconds from 0 hours, 0 minutes, 0 seconds UTC time on January 1, 1970 to the present. If t is not a null pointer, this function will also store the return value in the memory pointed to by t pointer.
Return value: Returns the number of seconds if successful, and ((time_t)-1) value if failed, and the error cause is stored in erron.

example:

1. #include<stdio.h>

2. main()

3. {

4. int i;

5. i=time((time_t*)NULL);

6. printf("%d",i);

7. }

blog:http://blog.csdn.net/wangluojisuan/article/details/7045592

2. Sleep function (function names and function parameter units may be different on different platforms and compilers)

Header file: #include <windows.h>

Define function: unsigned sleep(unsigned seconds);

Function Description: This function execution is suspended for a period of time.

Example: (For Windows+CodeBlocks, Sleep(), the unit is ms)

1. #include<stdio.h>

2. #include<windows.h>

3. main()

4. {

5. int i,j;

6. i=time((time_t*)NULL);

7. Sleep(2000); //延迟2s

8. j=time((time_t*)NULL);

9. printf("延时了%d秒",j-i);

10. }

blog: http://blog.csdn.net/jiangxinyu/article/details/7754664

3.clock function

Function definition: clock_t clock(void);

Function Description: The time the program occupies the CPU from startup to function call.

example:

1. #include<stdio.h>

2. #include<windows.h>

3. main()

4. {

5. int i,j;

6. Sleep(2000);

7. i=clock();

8. Sleep(2000);

9. j=clock();

10. printf("开始%d\n结束%d\n经过%d\n",i,j,j-i);

11. }