PHP functions and small knowledge points

<?PHP//Statement//Branch statement/*$a =5; if ($a ==5) {echo "equal";} else{echo "Budeng";}*///If//if...else//if...else. Nesting of if//if/*switch ($a) {case 1:echo "111"; Break    Case 2:echo "222";    Break    Case 3:echo "333";    Break    Case 4:echo "444";    Break    Default:echo "Default";    Break }*///Looping Statements/*For ($i =0; $i <10; $i + +) {echo $i. " <br> ";} $a =10;while ($a >0) {echo $a. "    <br> "; $a--;}*///function Four elements: return type, function name (initial capitalization), parameters, function body/function definition mode/*function Show () {echo "Hello";} Call function Show ();*///parametric functions/*function Show ($a, $b) {echo $a + $b;} Show (3,4,5)*///functions with default values/*function Show ($a =5, $b =5) {echo $a + $b;} Show ();*///functions with variable parameters/*function Show () {Func_get_args ();}    Gets the parameter $sum=0 of the function;     for ($i =0; $i <count ($attr)), $i + +)//Func_num__args () Gets the number of parameters {$sum = $sum + $attr [si]}; echo $sum;}*///functions that have return values/*function Show () {return "AAAA";} Echo Show ();*//*echo rand (0,100);//random number generation function*///Echo time ()///Date time taken is timestamp//echo date ("Y-m-d h:i:s" and Time ());//Format datetime//date_default_timezone_set (' PRC '); Method//echo Date ("Y-m-d h:i:s", Time ()),//echo strtotime ("2016-5-6"); Convert datetime format to timestamp//string processing function////$a = "Hello";//echo strlen ($a); Returns the string length *****//echo strcmp ("Hello", "Hello"); Compares two strings for equality, case-sensitive//echo strcasecmp ("AA", "AA"),//Compare two strings for equality, case-insensitive//echo strtolower ("HELLO");//convert string to lowercase *****/ /echo strtoupper ("Hello");//convert string to uppercase *****//$str = "Hello|world|join|on";//var_dump (Explode ("|", $str)); Depending on the delimiter, split the string, and the return is an array of *****//$attr =array ("AAA", "BBB", "CCC")//echo implode ("|", $attr); $str = "Hello|world|join|on";//echo substr_replace ($str, "AAA", 0,5)//Replace the string (replacing a position, where the position is determined by a subsequent parameter) *****//echo Str_replace ("L", "a", $str);//Find and replace *****//echo substr ($STR, 0,5); Intercept string *****//Some small knowledge points/*$a = "join"; $s 1= "hello\" {$a}world ";//1. Double quotes can use escape characters, single quotes cannot be used, output//2 as-is. Double quotes inside can parse variable, single quotation mark does not echo $s 1." <br/> "; $s 2= ' hello\" {$a}world '; Echo $s 2; Both single and double quotation marks can define a string,*///Defining a String (block)$str=<<<STR<div style= "Background-color:pink; color:white;width:100px;height:30px ">hello</div>STR;Echo $str; ?>

PHP functions and small knowledge points