{"id":173,"date":"2018-07-12T11:20:15","date_gmt":"2018-07-12T11:20:15","guid":{"rendered":"http:\/\/itp9.epgpbooks.inflibnet.ac.in\/?post_type=chapter&p=173"},"modified":"2018-12-07T11:00:14","modified_gmt":"2018-12-07T11:00:14","slug":"numbers-and-dates-with-php","status":"publish","type":"chapter","link":"https:\/\/ebooks.inflibnet.ac.in\/itp9\/chapter\/numbers-and-dates-with-php\/","title":{"rendered":"Numbers and Dates with PHP"},"content":{"raw":"
\"epgp<\/a>\r\n<\/span><\/div>\r\n
\r\n\r\n \r\n\r\n \r\n\r\n \r\n\r\nNumbers<\/strong>\r\n\r\n \r\n

Numbers can be integer or double. Integer number stores whole numbers. Integer number can have positive or negative sign. By default, is it positive, so the + sign can be omitted when write positive numbers. The maximum value for integer number is \u2013 2147483648 to +2147483647. PHP_INT_MAX constant is used by php to store this value. For example,<\/p>\r\n \r\n\r\n$max = PHP_INT_MAX;\r\n\r\necho \"Maximum value for PHP constant is: $max\";\r\n\r\nThen the output is:\r\n\r\nMaximum value for PHP constant is: 2147483647;\r\n\r\n \r\n

Floating point numbers are also known as floats, doubles or real numbers. Floating point number stores fraction value. To store a number as a floating point number, it must be written with .(decimal point). That means, if a variable assign a value 1 then the data type of a variable is treated as integer. A variable assign a value 1. (one with decimal point) then the data type of a variable is considered as double. Exponential notation can be used in double data type. The exponential notation is consisting of two parts. Mantissa and exponent. This number is written as mantissa e exponent. Mantissa can be integer or floating point number. The exponent must be integer number. The range for exponent is -307 to +308. The exponential notation expand to m * 10e. For example, 3.5e4 expand to 3.5* 104 means 3.5 * 10000 = 35000. In the same way -3.25e-2 expands -3.25*10(-2) = -3.25 * 1\/100 = -0.0325. In exponential form the sign of mantissa determine the overall number is positive or negative and the sign of exponent specifies that the number is large or small than 1.<\/p>\r\n \r\n

If the number is outside of the range of double value, then it is converted by positive or negative infinity. Positive infinity is represented by the constant named INF. Negative infinity is represented by the constant named \u2013INF. You can directly assign infinity to a variable or the result of an operation may be infinity. Generally, most operation where one operand is infinity, the result is infinity. The exception is when a value is divide by zero, it returns zero.<\/p>\r\n \r\n\r\nIn case you divide a value by zero, PHP generates warning.\r\n\r\n \r\n\r\nTo check whether the variable or expression is infinite, there are two functions available. These functions are:\r\n\r\n \r\n\r\n\r\n\r\n\r\n\r\n
Function<\/strong><\/td>\r\nDescription<\/strong><\/td>\r\n<\/tr>\r\n
is_infinite($value)<\/td>\r\nReruns true if the $value is infinite else false.<\/td>\r\n<\/tr>\r\n
is_finite($value)<\/td>\r\nReruns false if the $value is infinite else true.<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n \r\n\r\nFor example:\r\n\r\n \r\n\r\n$testinf = is_infinite(10*INF);\r\n\r\n<\/div>\r\n
\r\n

\u00a0 \u00a0echo \"<br> the value of '10 * INF' is : $testinf\";<\/p>\r\n

will display 1 on browser.<\/p>\r\n

In-Built useful Number Functions<\/strong><\/p>\r\n\"\"\r\n\r\n \r\n\r\nType Casting:<\/strong>\r\n\r\n \r\n

Type casting is used to convert one data type to another type. To type cast a value, write the data type in parentheses before the value. Below are few examples of type casting.<\/p>\r\n \r\n\r\n\/\/\u00a0\u00a0 Type casting\r\n\r\n$value = 31.8;\r\n\r\n$intcast = (int)$value;\r\n\r\necho \"<br> The original $value after casting to integer becomes: $intcast \";\r\n\r\n\/\/with string\r\n\r\n$value = \"31.8 Kilometers\"; \/\/ strings after the number is ignored $strint = (int)$value;<\/span>\r\n\r\necho \"<br> The original '$value' after casting to integer becomes: $strint \"; \/\/,<\/span>\r\n\r\n$value = \"31,000 Kilometers\";<\/span>\r\n\r\n$strint = (int)$value;<\/span>\r\n\r\necho \"<br> The original '$value' after casting to integer becomes: $strint \"; \/\/ string and number_format<\/span>\r\n\r\n$value = \"Kilometres 31,000\"; \/\/ strings which not start with number is converted to 0 $strint = (int)$value;<\/span>\r\n\r\necho \"<br> The original '$value' after casting to integer becomes: $strint \"; \/\/only string<\/span>\r\n\r\n$value = \"Kilometres\";<\/span>\r\n\r\n$strint = (int)$value;<\/span>\r\n\r\necho \"<br> The original '$value' after casting to integer becomes: $strint \"; \/\/out of range value<\/span>\r\n\r\n$value = '10000000000';<\/span>\r\n\r\n$strint = (int)$value;<\/span>\r\n\r\necho \"<br> The original '$value' after casting to integer becomes: $strint \";<\/span>\r\n\r\n \r\n\r\nThe output is:<\/span>\r\n\r\n<\/div>\r\n

\r\n\r\n \r\n\r\nThe original 31.8 after casting to integer becomes: 31\r\n\r\nThe original '31.8 Kilometers' after casting to integer becomes: 31\r\n\r\nThe original '31,000 Kilometers' after casting to integer becomes: 31\r\n\r\nThe original 'Kilometres 31,000' after casting to integer becomes: 0\r\n\r\nThe original 'Kilometres' after casting to integer becomes: 0\r\n\r\nThe original '10000000000' after casting to integer becomes: 2147483647\r\n\r\n \r\n\r\nSprintf<\/strong>\r\n\r\n<\/div>\r\n
\r\n\r\n \r\n

The sprint function is used to format strings and numbers. The general syntax of sprintf function is:<\/p>\r\n \r\n\r\nsprintf(format, $val1 [,$val2 \u2026.])\r\n\r\n \r\n

The format parameter can take any one value of for formatting $val. The format parameter can take any one of the following data type<\/p>\r\n \r\n\r\ns : string\r\n\r\nd : integer\r\n\r\nf:\u00a0 double\/decimal value\r\n\r\ne:\u00a0\u00a0 exponential notation\r\n

c:\u00a0\u00a0 convert integer value corresponding to equivalent ASCII character. The format-code must start with % symbol end ends with data type. Few examples for sprintf function is shown below.<\/p>\r\n\/\/sprintf examples\r\n\r\n$msg = sprintf(\"The book on %s has %d pages\",\"PHP\", 543);\r\n\r\necho \"<br> $msg\";\r\n\r\n$s1 = sprintf(\"%c\",65);<\/span>\r\n\r\necho \"<br> The ASCII character for value 65 is : $s1\";<\/span>\r\n\r\n$s2 = sprintf(\"%06d\",42);<\/span>\r\n\r\necho \"<br> The value 42 padded with 0 for length 0f 6 is: $s2\";<\/span>\r\n\r\n$date = sprintf(\"%02d-%02d-%04d\", 3,5,2015);<\/span>\r\n\r\necho \"<br> Print the date in DD-MM-YYYY format : $date\";<\/span>\r\n\r\n$s4 = sprintf(\"%09.2f\", 123.4567890);<\/span>\r\n\r\necho \"<br> The value is: $s4\";<\/span>\r\n\r\n<\/div>\r\n \r\n\r\nThe output of the above code is:<\/span>\r\n

\r\n\r\n \r\n\r\nThe book on PHP has 543 pages\r\n\r\nThe ASCII character for value 65 is : A\r\n\r\nThe value 42 paddedwith 0 for length 0f 6 is: 000042\r\n\r\nPrint the date in DD-MM-YYYY format : 03-05-2015\r\n\r\nThe value is: 000123.46\r\n\r\n \r\n\r\nDate:<\/strong>\r\n\r\n \r\n

PHP is used timestamp to display date and time. Timestamp stores an integer value, which stores the numbers of second since midnight on January 1, 1970 GMT (Greenwich Mean Time). This point of time is known as the Unix Epoch. Timestamp stored as a 32-bit signed integer number by most systems in the world. Hence these system timestamp can range from December 13, 1901 to January 19, 2038. When the system uses timestamps, reaches its upper limit January 19, 2038 its rolls over to the lower limit in 1901. When this may happens, it may create many problems. This problem is known as the year 2038 problem. This problem is similar to Y2K problem, so year 2038 problem is also known as Y2K38 problem. One way to solve the Y2K38 problem is to use DateTime objects. The DateTime object is explain later on.<\/p>\r\n \r\n\r\nTo create and format timestamp date( ) is used. The general syntax for date( ) function is:\r\n\r\n \r\n\r\nDate($format [, $timestamp])\r\n\r\n \r\n\r\nWhere $format represents various formatting option for date and $ts is a timestamp.\r\n\r\n \r\n

The date function returned the formatted timestamp. The format is specified in $format. By default the time stamp is current date and time. The $timestamp can be specified for any date or time.<\/p>\r\n \r\n\r\nFor example:\r\n\r\n \r\n\r\n$d = date('j-n-Y');\r\n\r\necho \"<br>Today is $d\";\r\n\r\ndisplay\r\n\r\nToday is 31-5-2015.\r\n\r\n \r\n

There are many formatting options available. Following table shows few formatting options.<\/p>\r\n \r\n\r\n<\/div>\r\n

\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n
Format<\/strong><\/td>\r\nDescription<\/strong><\/td>\r\n<\/tr>\r\n
j<\/td>\r\nDay of month without leading zero.<\/td>\r\n<\/tr>\r\n
d<\/td>\r\nDay of month with leading zero.<\/td>\r\n<\/tr>\r\n
D<\/td>\r\nDay of week in three letters (i.e.: Mon).<\/td>\r\n<\/tr>\r\n
l<\/td>\r\nDay of week full-name (i.e.: Monday)<\/td>\r\n<\/tr>\r\n
n<\/td>\r\nMonth number without leading zero<\/td>\r\n<\/tr>\r\n
m<\/td>\r\nMonth number with leading zero<\/td>\r\n<\/tr>\r\n
M<\/td>\r\nMonth name in three letters.<\/td>\r\n<\/tr>\r\n
S<\/td>\r\nOrdinal Suffix of a day<\/td>\r\n<\/tr>\r\n
F<\/td>\r\nFull Month Name.<\/td>\r\n<\/tr>\r\n
y<\/td>\r\nYear in two digits.<\/td>\r\n<\/tr>\r\n
Y<\/td>\r\nYear in four digits.<\/td>\r\n<\/tr>\r\n
L<\/td>\r\nLeap year or not. For leap year it is return 1<\/td>\r\n<\/tr>\r\n
<\/td>\r\notherwise 0.<\/td>\r\n<\/tr>\r\n
h<\/td>\r\nHours in 24 hour format without leading zero.<\/td>\r\n<\/tr>\r\n
g<\/td>\r\nHours in 12 hour format without leading zero.<\/td>\r\n<\/tr>\r\n
H<\/td>\r\nHours in 24 hour format with leading zero.<\/td>\r\n<\/tr>\r\n
G<\/td>\r\nHours in 12 hour format with leading zero<\/td>\r\n<\/tr>\r\n
i<\/td>\r\nMinutes with leading zero<\/td>\r\n<\/tr>\r\n
s<\/td>\r\nSeconds with leading zero<\/td>\r\n<\/tr>\r\n
A<\/td>\r\nAM\/PM in uppercase<\/td>\r\n<\/tr>\r\n
a<\/td>\r\nam\/pm in lowercase<\/td>\r\n<\/tr>\r\n
U<\/td>\r\nSeconds since unix epoch<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n \r\n\r\nFor example,\r\n\r\n$d = date('j-n-Y \\a\\t H:i A ');\r\n\r\necho \"<br>Today is $d\";\r\n\r\nwill display\r\n\r\nToday is 31-5-2015 at 08:57 AM\r\n\r\nToday is 31-5-2015 at 08:57 AM\r\n\r\n \r\n

Useful functions for working with Timestamps<\/strong><\/p>\r\n \r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n
Function<\/strong><\/td>\r\nDescription<\/strong><\/td>\r\n<\/tr>\r\n
time()<\/td>\r\nReturns current date time as timestamp<\/td>\r\n<\/tr>\r\n
mktime([$h [,$m [,$s [,$M [,$D [,$Y]]]]]])\r\n\r\n \r\n\r\n \r\n\r\n <\/td>\r\nReturns\u00a0\u00a0 timestamp\u00a0\u00a0 based\u00a0\u00a0 on\u00a0\u00a0 the\r\n\r\nparameters\u00a0 passed.\u00a0 If\u00a0 any\u00a0 parameter\u00a0 is\r\n\r\nskipped, then the value of current date and\r\n\r\ntime is set.<\/td>\r\n<\/tr>\r\n
checkdate($M,$D,$Y)\r\n\r\n <\/td>\r\nReturns true if the $M (month), $D (date)\r\n\r\nand $Y (year) provide valid date.<\/td>\r\n<\/tr>\r\n
getdate([$ts])\r\n\r\n <\/td>\r\nReturns\u00a0 an\u00a0 array\u00a0 having\u00a0 parts\u00a0 of\u00a0 time\r\n\r\nstamp. If $ts is omitted, it uses current\u00a0date and time<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\n
\r\n\r\n \r\n\r\nFollowing code shows use of timestamp functions:<\/strong>\r\n\r\n \r\n\r\n$ts = time();\r\n\r\n \r\n\r\necho \"<br>The value of current time stamp is : $ts\"; $mts = mktime(10, 10, 00,13, 4, 2012 );\r\n\r\n \r\n\r\necho \"<br>The new time stamp has value: $mts\"; $chkdt = checkdate(11,30,2015);\r\n\r\n \r\n\r\necho \"<br> 30 Novemebr 2015 by checkdate returns: $chkdt <br>\";\r\n\r\n \r\n\r\nThen the output will be:\r\n\r\n \r\n\r\nThe value of current time stamp is : 1433058159\r\n\r\n \r\n\r\nThe new time stamp has value: 1357290600\r\n\r\n \r\n\r\n30 November 2015 by checkdate returns: 1\r\n\r\n \r\n\r\nYou can find many timestamp functions at PHP manual on the web.\r\n\r\n \r\n\r\nStrtotime function in PHP<\/strong>\r\n\r\n \r\n\r\nThe strtotime function returns timestamp for a string. The general syntax is\r\n\r\n \r\n\r\nStrtotime($str [,$ts])\r\n\r\n \r\n

If timestamp $ts is omitted, then this functions consider current date and time as timestamp. Whenever timestamp $ts is specified, then it works relative to specified timestamp $ts. The strtotime functions supports most of the date and time formats and most relative time specifications.<\/p>\r\n \r\n\r\nBelow shows few examples of absolute templates used with strtotime function.\r\n\r\n \r\n\r\n$date1 = strtotime('2015-06-01'); \/\/Mon June 1 2015 00:00\r\n\r\n$date2 = strtotime(\u2018Jun 1\u2019); \/\/Mon June 1 2015 00:00\r\n\r\n$date3 = strtotime(\u20186:45\u2019); \/\/ Mon June 1 2015 6:45\r\n\r\n \r\n\r\nThe following code snippets represent relative templates with strtotime function.\r\n\r\n \r\n\r\n\/\/Assume that the current date time is 06\/01\/2015 10:44:00 PM (June 1, 2015)\r\n\r\n \r\n\r\n$date4 = strtotime('+1 hour');\u00a0\u00a0\u00a0 \/\/Mon 06\/01\/2015 11:44:00 PM\r\n\r\n<\/div>\r\n

\r\n\r\n\u00a0 \u00a0 $date5 = strtotime(\u2018-2 days\u2019);\u00a0\u00a0\u00a0 \/\/Sat 05\/30\/2015 11:44:00 PM\r\n\r\n \r\n\r\n$date6 = strtotime(\u2018next Sunday\u2019)\u00a0 \/\/Sun 06\/07\/2015 00:00\r\n\r\n \r\n\r\nDatetime<\/strong>\r\n