To calculate how many days in a particular month of a year PHP provides in build function cal_days_in_month() function returns the number of days in a month for a specified year and calendar.
The array_filter() function use to filters the elements of an array using a callback function. This function accepts two parameters and one flag. The first parameter is required which is to be an array
The usort() function sort an array by values using a user-defined comparison function. It accepts two parameters, the first parameter
The array_diff() function compares ar1 against one or more other arrays and returns the values in ar2 that are not
array_push() function use an array as a stack, and it pushes the passed variables at the end of the array.