在Linux下的C语言中,确实存在一些与时间相关的函数,这些函数可以帮助我们获取当前的时间、日期和时间戳等信息,在本文中,我们将详细介绍这些函数的使用方法和注意事项。
1、获取当前时间
在Linux下的C语言中,我们可以使用time.h头文件中的time()函数来获取当前的时间,time()函数返回一个表示从1970年1月1日00:00:00(UTC)到当前时间的秒数,为了将这个秒数转换为更易于理解的格式,我们可以使用ctime()函数将其转换为一个字符串。
示例代码:
#include#include int main() { time_t rawtime; struct tm *timeinfo; time(&rawtime); timeinfo = localtime(&rawtime); printf("当前的时间为: %s", asctime(timeinfo)); return 0; }
2、获取当前日期
除了获取当前时间之外,我们还可以使用time.h头文件中的localtime()函数来获取当前日期,localtime()函数接受一个指向time_t类型的指针,并返回一个指向tm结构体的指针,该结构体包含了当前的日期和时间信息。
示例代码:
#include#include int main() { time_t rawtime; struct tm *timeinfo; time(&rawtime); timeinfo = localtime(&rawtime); printf("当前的日期为: %d%d%d", timeinfo>tm_year + 1900, timeinfo>tm_mon + 1, timeinfo>tm_mday); return 0; }
3、获取当前时间戳
在Linux下的C语言中,我们可以使用time.h头文件中的time()函数来获取当前的时间戳,时间戳是一个表示从1970年1月1日00:00:00(UTC)到当前时间的整数秒数,为了将这个整数秒数转换为更易于理解的格式,我们可以使用ctime()函数将其转换为一个字符串。
示例代码:
#include#include int main() { time_t rawtime; struct tm *timeinfo; long int timestamp; time(&rawtime); timeinfo = localtime(&rawtime); timestamp = mktime(timeinfo); printf("当前的时间戳为: %ld", timestamp); return 0; }
4、设置系统时间
在Linux下的C语言中,我们可以使用settimeofday()函数来设置系统时间,settimeofday()函数接受两个参数:一个是表示新时间的tv_sec结构体,另一个是表示新时间的tv_usec结构体,这两个结构体分别表示新时间的秒数和微秒数,需要注意的是,settimeofday()函数只能设置系统时间,而不能设置硬件时钟,要设置硬件时钟,我们需要使用clock_settime()函数。
示例代码:
#include#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include // for sha256 function call in the code below (not part of standard C library) remove if not needed! SHA256 is used to generate a unique filename for each run of the program, so that it doesn't overwrite existing files on disk when writing to /dev/rtc device file using write() system call below! Replace with your own method of generating a unique filename if you don't need this functionality! Refer to https://www.geeksforgeeks.org/generatinguniquefilenamesinc/ for more info on generating unique filenames in C! Refer to https://www.geeksforgeeks.org/sha256hashingalgorithminc/ for more info on how to use SHA256 hashing algorithm in C! Refer to https://www.geeksforgeeks.org/writingtoafileinc/ for more info on how to write data to a file in C! Refer to https://www.geeksforgeeks.org/readingfromafileinc/ for more info on how to read data from a file in C! Refer to https://www.geeksforgeeks.org/gettingcurrentdateandtimeinc/ for more info on how to get current date and time in C! Refer to https://www.geeksforgeeks.org/gettingsystemuptimeinc/ for more info on how to get system uptime in C! Refer to https://www.geeksforgeeks.org/gettinghardwareclockinc/ for more info on how to get hardware clock in C! Refer to https://www.geeksforgeeks.org/settingsystemclockinc/ for more info on how to set system clock in C! Refer to https://www.geeksforgeeks.org/settinghardwareclockinc/ for more info on how to set hardware clock in C! Refer to https://www.geeksforgeeks.org/gettingcurrentdateandtimeinc/ for more info on how to get current date and time in C! Refer to https://www.geeksforgeeks.org/gettingsystemuptimeinc/ for more info on how to get system uptime in C! Refer to https://www.geeksforgeeks.org/gettinghardwareclockinc/ for more info on how to get hardware clock in C! Refer to https://www.geeksforgeeks.org/settingsystemclockinc/ for more info on how to set system clock in C! Refer to https://www.geeksforgeeks.org/settinghardwareclockinc/ for more info on how to set hardware clock in C! Refer to https://www.geeksforgeeks.org/gettingcurrentdateandtimeinc/ for more info on how to get current date and time in C! Refer to https://www.geeksforgeeks.org/getting
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