time_t is signed int/long

最新推荐文章于 2023-01-08 21:53:51 发布

hushui

最新推荐文章于 2023-01-08 21:53:51 发布

阅读量172

点赞数

分类专栏： GCC

本文链接：https://blog.youkuaiyun.com/hushui/article/details/117551109

版权

GCC 专栏收录该内容

26 篇文章

订阅专栏

时间_t是ISO C标准定义的一种用于存储系统时间的数值类型，通常由time()函数返回。虽然ISO C未指定其具体类型、范围、分辨率或编码，但在Unix和POSIX兼容系统中，它被实现为一个带符号整数（通常是32或64位），表示自1970年1月1日（不包括闰秒）以来的秒数。32位实现可能会遇到2038年问题。在X86_64位Centos7系统中，time_t被typedef为long int。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

The time_t datatype is a data type in the ISO C library defined for storing system time values. Such values are returned from the standard time() library function. This type is a typedef defined in the standard header. ISO C defines time_t as an arithmetic type, but does not specify any particular type, range, resolution, or encoding for it. Also unspecified are the meanings of arithmetic operations applied to time values.

Unix and POSIX-compliant systems implement the time_t type as a signed integer (typically 32 or 64 bits wide) which represents the number of seconds since the start of the Unix epoch: midnight UTC of January 1, 1970 (not counting leap seconds). Some systems correctly handle negative time values, while others do not. Systems using a 32-bit time_t type are susceptible to the Year 2038 problem.

## X86_64bit Centos7

[lhu3@zch127bld08 source]$ g++ -E time_t_is_signed.cpp | grep __time_t
typedef long int __time_t;
typedef __time_t time_t;
__time_t tv_sec;
__time_t tv_sec;