* 字符串格式化
The format string consists of format codes followed by an optional repeater argument. The repeater argument can be either an integer value or * for repeating to the end of the input data. For a, A, h, H the repeat count specifies how many characters of one data argument are taken, for @ it is the absolute position where to put the next data, for everything else the repeat count specifies how many data arguments are consumed and packed into the resulting binary string.
Currently implemented formats are:
| Code | Description |
|---|---|
| a | NUL-padded string |
| A | SPACE-padded string |
| h | Hex string, low nibble first |
| H | Hex string, high nibble first |
| c | signed char |
| C | unsigned char |
| s | signed short (always 16 bit, machine byte order) |
| S | unsigned short (always 16 bit, machine byte order) |
| n | unsigned short (always 16 bit, big endian byte order) |
| v | unsigned short (always 16 bit, little endian byte order) |
| i | signed integer (machine dependent size and byte order) |
| I | unsigned integer (machine dependent size and byte order) |
| l | signed long (always 32 bit, machine byte order) |
| L | unsigned long (always 32 bit, machine byte order) |
| N | unsigned long (always 32 bit, big endian byte order) |
| V | unsigned long (always 32 bit, little endian byte order) |
| f | float (machine dependent size and representation) |
| d | double (machine dependent size and representation) |
| x | NUL byte |
| X | Back up one byte |
| @ | NUL-fill to absolute position |
* 日期时间格式化
format character | Description | Example returned values |
|---|---|---|
| Day | --- | --- |
| d | Day of the month, 2 digits with leading zeros | 01 to 31 |
| D | A textual representation of a day, three letters | Mon through Sun |
| j | Day of the month without leading zeros | 1 to 31 |
| l (lowercase 'L') | A full textual representation of the day of the week | Sunday through Saturday |
| N | ISO-8601 numeric representation of the day of the week (added in PHP 5.1.0) | 1 (for Monday) through 7 (for Sunday) |
| S | English ordinal suffix for the day of the month, 2 characters | st, nd, rd or th. Works well with j |
| w | Numeric representation of the day of the week | 0 (for Sunday) through 6 (for Saturday) |
| z | The day of the year (starting from 0) | 0 through 365 |
| Week | --- | --- |
| W | ISO-8601 week number of year, weeks starting on Monday (added in PHP 4.1.0) | Example: 42 (the 42nd week in the year) |
| Month | --- | --- |
| F | A full textual representation of a month, such as January or March | January through December |
| m | Numeric representation of a month, with leading zeros | 01 through 12 |
| M | A short textual representation of a month, three letters | Jan through Dec |
| n | Numeric representation of a month, without leading zeros | 1 through 12 |
| t | Number of days in the given month | 28 through 31 |
| Year | --- | --- |
| L | Whether it's a leap year | 1 if it is a leap year, 0 otherwise. |
| o | ISO-8601 year number. This has the same value as Y, except that if the ISO week number (W) belongs to the previous or next year, that year is used instead. (added in PHP 5.1.0) | Examples: 1999 or 2003 |
| Y | A full numeric representation of a year, 4 digits | Examples: 1999 or 2003 |
| y | A two digit representation of a year | Examples: 99 or 03 |
| Time | --- | --- |
| a | Lowercase Ante meridiem and Post meridiem | am or pm |
| A | Uppercase Ante meridiem and Post meridiem | AM or PM |
| B | Swatch Internet time | 000 through 999 |
| g | 12-hour format of an hour without leading zeros | 1 through 12 |
| G | 24-hour format of an hour without leading zeros | 0 through 23 |
| h | 12-hour format of an hour with leading zeros | 01 through 12 |
| H | 24-hour format of an hour with leading zeros | 00 through 23 |
| i | Minutes with leading zeros | 00 to 59 |
| s | Seconds, with leading zeros | 00 through 59 |
| u | Microseconds (added in PHP 5.2.2) | Example: 654321 |
| Timezone | --- | --- |
| e | Timezone identifier (added in PHP 5.1.0) | Examples: UTC, GMT, Atlantic/Azores |
| I (capital i) | Whether or not the date is in daylight saving time | 1 if Daylight Saving Time, 0 otherwise. |
| O | Difference to Greenwich time (GMT) in hours | Example: +0200 |
| P | Difference to Greenwich time (GMT) with colon between hours and minutes (added in PHP 5.1.3) | Example: +02:00 |
| T | Timezone abbreviation | Examples: EST, MDT ... |
| Z | Timezone offset in seconds. The offset for timezones west of UTC is always negative, and for those east of UTC is always positive. | -43200 through 50400 |
| Full Date/Time | --- | --- |
| c | ISO 8601 date (added in PHP 5) | 2004-02-12T15:19:21+00:00 |
| r | » RFC 2822 formatted date | Example: Thu, 21 Dec 2000 16:01:07 +0200 |
| U | Seconds since the Unix Epoch (January 1 1970 00:00:00 GMT) | See also time() |
Unrecognized characters in the format string will be printed as-is. The Z format will always return 0 when using gmdate().