DateInterval::__construct Creates a new DateInterval object &reftitle.description; public DateInterval::__construct stringduration Creates a new DateInterval object. &reftitle.parameters; duration An interval specification. The format starts with the letter P, for period. Each duration period is represented by an integer value followed by a period designator. If the duration contains time elements, that portion of the specification is preceded by the letter T. Period Designator Description Y years M months D days W weeks. Converted into days. Prior to PHP 8.0.0, can not be combined with D. H hours M minutes S seconds Here are some simple examples. Two days is P2D. Two seconds is PT2S. Six years and five minutes is P6YT5M. The unit types must be entered from the largest scale unit on the left to the smallest scale unit on the right. So years before months, months before days, days before minutes, etc. Thus one year and four days must be represented as P1Y4D, not P4D1Y. The specification can also be represented as a date time. A sample of one year and four days would be P0001-00-04T00:00:00. But the values in this format can not exceed a given period's roll-over-point (e.g. 25 hours is invalid). These formats are based on the ISO 8601 duration specification. &reftitle.errors; Throws an DateMalformedIntervalStringException when the duration cannot be parsed as an interval. Prior to PHP 8.3, this was Exception. &reftitle.changelog; &Version; &Description; 8.3.0 Now throws DateMalformedIntervalStringException instead of Exception. 8.2.0 Only the y to f, invert, and days will be visible, including a new from_string boolean property. 8.0.0 W can be combined with D. &reftitle.examples; add($interval); // Convert interval to string echo $interval->format("%d"); ]]> &example.outputs; 7 ]]> &example.outputs.82; int(0) ["m"]=> int(0) ["d"]=> int(9) ["h"]=> int(0) ["i"]=> int(0) ["s"]=> int(0) ["f"]=> float(0) ["invert"]=> int(0) ["days"]=> bool(false) ["from_string"]=> bool(false) } ]]> &example.outputs.8; int(0) ["m"]=> int(0) ["d"]=> int(9) ["h"]=> int(0) ["i"]=> int(0) ["s"]=> int(0) ["f"]=> float(0) ["weekday"]=> int(0) ["weekday_behavior"]=> int(0) ["first_last_day_of"]=> int(0) ["invert"]=> int(0) ["days"]=> bool(false) ["special_type"]=> int(0) ["special_amount"]=> int(0) ["have_weekday_relative"]=> int(0) ["have_special_relative"]=> int(0) } ]]> &example.outputs.7; int(0) ["m"]=> int(0) ["d"]=> int(2) ["h"]=> int(0) ["i"]=> int(0) ["s"]=> int(0) ["f"]=> float(0) ["weekday"]=> int(0) ["weekday_behavior"]=> int(0) ["first_last_day_of"]=> int(0) ["invert"]=> int(0) ["days"]=> bool(false) ["special_type"]=> int(0) ["special_amount"]=> int(0) ["have_weekday_relative"]=> int(0) ["have_special_relative"]=> int(0) } ]]> &reftitle.seealso; DateInterval::format DateTime::add DateTime::sub DateTime::diff