PHP calculates the day of the week today for the previous month.

Today of the previous month

Strtotime has a small problem

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> Php-r "echo date ('ymd000000 & prime;, strtotime ('-1 month', strtotime ('2017 & prime ;)));" 20130701000000 # > Php-r "echo date ('ymd000000 & prime;, strtotime ('-1 month', strtotime ('2017 & prime ;)));" 20130701000000 #

Now, I think that PHP has a mktime function, so I wrote the following code:

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Echo date ("Y-m-d H: I: s", mktime (date ("G", $ time), date ("I", $ time ), Date ("s", $ time), date ("n", $ time)-1, date ("j", $ time), date ("Y ", $ time )));

When executed, it is found that the results are the same as those of strtotime.

 

After searching, the following methods are more accurate.

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$ Time = strtotime ("2011-03-31 "); /** * Calculate the current day of the previous month. If the previous month does not have today, return the last day of the previous month. * @ Param type $ time * @ Return type */ Function last_month_today ($ time ){ $ Last_month_time = mktime (date ("G", $ time), date ("I", $ time ), Date ("s", $ time), date ("n", $ time), 0, date ("Y", $ time )); $ Last_month_t = date ("t", $ last_month_time ); If ($ last_month_t <date ("j", $ time )){ Return date ("Y-m-t H: I: s", $ last_month_time );     } Return date ("Y-m", $ last_month_time). "-d", $ time ); } Echo last_month_today ($ time );

Note the following code: date ("Y-m", $ last_month_time). "-d. During code writing, if "Y-". date ("m", $ last_month_time). "-d" is written, there is a problem with the time of the new year.

Today is the day of the week

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<? Php echo date ('Y-m-D', strtotime ('-1 month');?>

Well... It seems to be right... but there is a problem with this function,
If the number of days in a month is different, the result is incorrect.
Join today is. The result of the calculation last month is;
PHP has a function mktime, which can get the timestamp of the date:
Int mktime ([int $ hour [, int $ minute [, int $ second [, int $ month [, int $ day [, int $ year [, int $ is_dst])
Returns the Unix timestamp based on the given parameters. The timestamp is a long integer that contains the number of seconds from the Unix epoch (January 1 1970 00:00:00 GMT) to the given time.

The parameter can be omitted from the right to the left. Any omitted parameter is set to the current value of the local date and time.
So we can use it to calculate

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Function last_month_day ($ time ){ $ Strtime = mktime (date ('H', $ time), date ('I', $ time), date ('s', $ time ), date ('M', $ time)-1, date ('D', $ time), date ('Y', $ time )); Echo date ('Y-m-D', $ strtime);} last_month_day (strtotime ("2012-03-31 "));

The output result is. The output is ???? Are there any February dummies? No. Is there a 30th number? Are there on the 29th ?.. This...
PHP handles this situation for us. It will take several more days to calculate it by the next month.
The last day of June is February 2012, so the 31st day is two days later than that of June 29, so PHP will be added to the next month to handle the problem on May 29.
I almost forgot. How can I calculate the day of the week ?? You don't have to worry about it. PHP is ready for us.
Date ('W', $ strtime );The day of the week is the day of the week.