C++ 检查日期是否有效
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C++ check if a date is valid
提问by MBZ
is there any function to check if a given date is valid or not? I don't want to write anything from scratch.
是否有任何功能可以检查给定日期是否有效？我不想从头开始写任何东西。
e.g. 32/10/2012 is not valid and 10/10/2010 is valid
例如 32/10/2012 无效而 10/10/2010 有效
采纳答案by spencercw
If your string is always in that format the easiest thing to do would be to split the string into its three components, populate a tmstructure and pass it to mktime(). If it returns -1 then it's not a valid date.
如果您的字符串始终采用该格式，最简单的做法是将字符串拆分为其三个部分，填充一个tm结构并将其传递给mktime(). 如果它返回 -1，那么它不是一个有效的日期。
You could also use Boost.Date_Timeto parse it:
您还可以使用Boost.Date_Time来解析它：
string inp("10/10/2010");
string format("%d/%m/%Y");
date d;
d = parser.parse_date(inp, format, svp);
回答by Alikar
The boost date time class should be able to handle what you require. See http://www.boost.org/doc/libs/release/doc/html/date_time.html
提升日期时间类应该能够处理您的需求。请参阅http://www.boost.org/doc/libs/release/doc/html/date_time.html
回答by netcoder
If the format of the date is constant and you don't want to use boost, you can always use strptime, defined in the ctimeheader:
如果日期的格式是常量并且您不想使用 boost，则可以始终使用strptime, 在ctime标题中定义：
const char date1[] = "32/10/2012";
const char date2[] = "10/10/2012";
struct tm tm;
if (!strptime(date1, "%d/%m/%Y", &tm)) std::cout << "date1 isn't valid\n";
if (!strptime(date2, "%d/%m/%Y", &tm)) std::cout << "date2 isn't valid\n";
回答by Jim Fell
If the slashes are inserted programatically (I would assume so, since you're assuming that they'll always be there.), it would probably be best to validate the month, day, and year separately. For example:
如果以编程方式插入斜杠（我会这样假设，因为您假设它们将始终存在。），最好分别验证月、日和年。例如：
if ( (month < 1) || (month > 12) ) return false;
