Detailed explanation of strtotime() function in PHP time operation

PHP is a scripting language for web development. It is not only flexible in development and easy to use, but also has very practical time operation functions. Among them, strtotime() is a very commonly used time operation function in PHP, which can convert time in string format into a timestamp. This article will explain this function in detail.

1. Function of strtotime() function

The strtotime() function is a very practical PHP time operation function. Its main function is to convert string type time into timestamp type.

2. strtotime() function format

The parameter format of strtotime() function is very diverse, which can be hours, minutes, seconds, days, weeks, months, etc., which allows us to perform various functions on time. different operations. The following is the usage format of this function:

strtotime(string $time, [int $now]);

Among them, $time refers to the timestamp string, which must be in English or the default time Format to describe; $now refers to the current system time, this parameter does not need to be passed in, if not passed in, the current time will be used by default.

3. strtotime() function syntax example

The following are some commonly used strtotime() function examples. The specific usage can be understood through the following examples:

1. Convert the current time to timestamp format

$curr_time = strtotime('now');
echo $curr_time;

//The output result is: 1565605379

2 .Convert the specified time string into timestamp format

$assign_time = strtotime('2019-08-12 12:12:12');
echo $assign_time;

/ / The output result is: 1565595132

3. Convert the time after the specified number of days into timestamp format

$assign_day = strtotime('-2 day');
echo $assign_day;

//The output result is: 1565425379
// Here is the current time minus two days

4. Convert the time after the specified month into a timestamp format

$assign_month = strtotime(' 1 month');
echo $assign_month;

// The output result is: 1568193379
// Here is the current time plus one month

5. Convert the time after a certain hour of the specified time into timestamp format

$assign_hour = strtotime(' 4 hour');
echo $assign_hour;

//The output result is: 1565627779
// Here is the current time plus four hours

6. Convert the Tuesday time after a certain day of the specified time into the timestamp format

$assign_day = strtotime('next tuesday');
echo $assign_day;

//The output result is: 1565818800
//This is the time of the next Tuesday at the current time

4. Precautions for the strtotime() function

Although the strtotime() function is simple and convenient to use, you still need to pay attention to some precautions during use:

1. The string format must be correct, Otherwise, false will be returned.

2. If the $now parameter is not passed in, the current system time will be used by default.

3. This function does not support timestamps greater than 2038 because integer overflow occurs.

5. Summary

The strtotime() function is a very practical PHP time operation function both in the development process and in the production environment. It can easily convert string type time Convert to timestamp type and perform various operations on time format, which is very convenient during the development process. During use, you need to pay attention to the correct transmission of parameters and whether the overflow of the timestamp integer type is supported.

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