Detailed explanation of the use of strtotime time function in php-PHP Tutorial-php.cn

Detailed explanation of the use of strtotime time function in php

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Release： 2016-07-25 08:59:20

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echo date("Y-m-d H:i:s", strtotime("feb", strtotime("2011-03-31")));

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The program will output: 2011- 03-03 00:00:00. From the appearance point of view, this result may not necessarily be what we want, but it can also be regarded as a solution. What determines this solution? The strtotime function performs month calculations Only the month is calculated, which is equivalent to directly setting the month to the value of the specified month. For example, jan and January will have a corresponding internal value.

2. first keyword first is an auxiliary keyword, which can be used in combination with keywords such as week, day, etc. that can specify a confirmation value, such as finding the first Sunday in 2011:

echo date("Y-m-d H:i:s", strtotime("second sunday", strtotime("2011-01-01"))), "
";

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In the PHP source code, the combined use of first, week and day is separate, that is, first day corresponds to a processing operation. In the final C implementation, the value of day is specified as 1, that is, in the time structure The d field is specified as 1, as shown in the following code:

switch (time->relative.first_last_day_of) {
case 1: /* first */
time->d = 1;
break;
case 2: /* last */
time- >d = 0;
time->m++;
break;
}

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3, previous and next keywords Similar to first, the previous keyword can be used in combination with week and day to indicate the day of the week or day before the specified time. The code is as follows:

echo date("Y-m-d H:i:s", strtotime("previous sunday", strtotime("2011-02-01"))), "
";

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The program will output: 2011-01-30 00:00:00 The program seeks the Sunday before 2011-02-01. The next keyword is the opposite of previous, it represents the next day of the week or the day after.

4. last keyword The last keyword can be used as either the previous or the last one. To find the date of the previous Sunday:

echo date("Y-m-d H:i:s", strtotime("last sunday", strtotime("2011-02-05"))), "
";

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The program will output: 2011-01-30 00:00:00 When the program is used as the last, its application scenario is the last day of the month where the specified date is located, which is equivalent to the result of date("t"). For the last day of February 2000:

echo date("Y-m-d H:i:s", strtotime("last day", strtotime("2000-02-01"))), "
";

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first, previous, last and this keywords belong to the same group in the re file.

5. back and front keywords These two keywords are forward and backward operations on the hours of the day, and their calling format is as follows:

echo date("Y-m-d H:i:s", strtotime("back of 24", strtotime("2011-02-01"))), "
";
echo date("Y-m-d H:i:s", strtotime("front of 24", strtotime("2011-02-01"))), "
";

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back means setting the time to 15 minutes of the hour after the specified hour value. If it is 24:00, it will be counted to 0:15 of the next day. front means to set the time to 45 minutes of the hour before the specified hour value. If it is 0 o'clock, it is calculated as 23:45 of the previous day. The above code outputs: 2011-02-02 00:15:00 2011-02-01 23:45:00. The arrays followed by back of and front of must be greater than or equal to 0 and less than or equal to 24. Basic principles of implementation of strtotime function The official documentation describes the strtotime function as follows: This function is expected to accept a string containing a US English date format and try to parse it into a Unix timestamp (the number of seconds since January 1 1970 00:00:00 GMT ), its value is relative to the time given by the now parameter. If this parameter is not provided, the current system time is used. This is a standard PHP built-in function that has existed since PHP4. The strtotime function is loaded as an extension, and its full implementation is available in the ext/date directory. As a standard built-in function, its definition format is also standard. , as follows:

PHP_FUNCTION(strtotime)
//Process input, whether there is a second parameter or not
//Call related functions to implement string parsing and result calculation
//Return results
}

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In input processing, first identify the situation where both parameters exist and process it. If it is not in this state, process the situation where the second parameter does not exist. If neither parameter exists, report an error and return FALSE. 1 2 Next Page Last Page