strftime() – C语言库函数
C库函数 size_t strftime(char *str, size_t maxsize, const char *format, const struct tm *timeptr) 格式表示的时间结构timeptr根据定义格式并存储到str格式规则。
声明
以下是strftime() 函数的声明。
size_t strftime(char*str,size_t maxsize,constchar*format,conststruct tm *timeptr)
参数
-
str -- 这是C字符串复制到目标数组的指针。
-
maxsize -- 这是给 str 要复制的字符的最大数目。
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format -- 这是C字符串，其中包含常规字符和特殊格式说明符的任意组合。这些格式说明符该函数相应的值代替 tm 中指定的时间来表示。格式说明符：
| 指示符 | 取代 | 例子 |
|---|---|---|
| %a | Abbreviated weekday name | Sun |
| %A | Full weekday name | Sunday |
| %b | Abbreviated month name | Mar |
| %B | Full month name | March |
| %c | Date and time representation | Sun Aug 19 02:56:02 2012 |
| %d | Day of the month (01-31) | 19 |
| %H | Hour in 24h format (00-23) | 14 |
| %I | Hour in 12h format (01-12) | 05 |
| %j | Day of the year (001-366) | 231 |
| %m | Month as a decimal number (01-12) | 08 |
| %M | Minute (00-59) | 55 |
| %p | AM or PM designation | PM |
| %S | Second (00-61) | 02 |
| %U | Week number with the first Sunday as the first day of week one (00-53) | 33 |
| %w | Weekday as a decimal number with Sunday as 0 (0-6) | 4 |
| %W | Week number with the first Monday as the first day of week one (00-53) | 34 |
| %x | Date representation | 08/19/12 |
| %X | Time representation | 02:50:06 |
| %y | Year, last two digits (00-99) | 01 |
| %Y | Year | 2012 |
| %Z | Timezone name or abbreviation | CDT |
| %% | A % sign | % |
-
timeptr -- 这是为tm结构的指针，它包含一个日历时间分解成其组成部分，如下图所示：
struct tm {int tm_sec;/* seconds, range 0 to 59 */int tm_min;/* minutes, range 0 to 59 */int tm_hour;/* hours, range 0 to 23 */int tm_mday;/* day of the month, range 1 to 31 */int tm_mon;/* month, range 0 to 11 */int tm_year;/* The number of years since 1900 */int tm_wday;/* day of the week, range 0 to 6 */int tm_yday;/* day in the year, range 0 to 365 */int tm_isdst;/* daylight saving time */};
返回值
如果C字符串适合大小的字符（包括终止空字符）小于总数的字符复制到 str（不包括终止空字符），否则返回0。
例子
下面的例子演示了如何使用strftime() 函数。
#include<stdio.h>#include<time.h>int main (){time_t rawtime;struct tm *info;char buffer[80]; time(&rawtime ); info = localtime(&rawtime ); strftime(buffer,80,"%x - %I:%M%p", info); printf("Formatted date & time : |%s| ", buffer );return(0);}
让我们编译和运行上面的程序，这将产生以下结果：
Formatted date & time : |08/23/12 - 12:40AM|