PHP Learning Note Nine "array two"

<! DOCTYPE HTML Public"-//w3c//dtd HTML 4.01 frameset//en" "Http://www.w3.org/TR/html4/frameset.dtd" >PHP$arr[0]=1; $arr[1]= "Hello World"; $arr[2]=true; $arr[3]=45.45; //the value of the PHP array can be any type of   for($i= 0;$i<Count($arr);$i++)  {   Echo"<br/>".$arr[$i]; }    //the second way of the array  Echo' <br/> the second way to create an array '; $arr 1=Array(1, "Hello World", 23.4,false);  for($j= 0;$j<Count($arr 1);$j++)  {    Echo"<br>".$arr 1[$j]; }    //the third way of the array is to specify key, by default the key is 0  $arr 2["Test1"]= "Hello"; $arr 2["Test2"]= "World"; $arr 2["Num"]= "34";  for($z= 0;$z<Count($arr 2);$z++)  {    Echo"<br/>".$arr 2[$z];//when you specify a key, you cannot traverse it in this way, only with foreach convenience  }  Echo"<br/> cannot traverse with for, only use foreach"; //foreach uses a wider range of essays  foreach($arr 2  as $val)  {   Echo"<br/>".$val; }    Echo"<br/>". Output Key "; foreach($arr 2  as $key=$val)  {   Echo"<br/>".$key." =".$val." <br/> "; }    //*********************  $arr 3[true]= "Hello";//If you use True as key then you need to access $arr 3[1]  $arr 3[false]= "World";//If you use false as key then Access $arr 3[0]  $arr 3[NULL]= "Beijing";//If you use NULL as key, you can use null and "" to access $arr3[null] or $arr 3[""];  Echo"<br/> access an array of true,false,null as key"; Echo $arr 3[NULL]; Echo $arr 3[""]; //*********************   $arr 4[123.4]= "Hello World"; Echo"<br/>".$arr 4[123.4]; Echo"<br/>".$arr 4[123]; Echo"<br/>"; Print_r($arr 4);//print_r output Array information    Echo"<br/>"; Var_dump($arr 4);//var_dump can output array information in more detail//*********************   Echo"The array of <br/>php is dynamically growing"; $arr 5=Array(2,3); $arr 5[2]= "Hello World"; $arr 5[5]= "Beijing";//this array will not error, but 3,4 no use, but not through $arr5[3] to access   foreach($arr 5  as $val)   {    Echo"<br/>".$val; }  //******************** to determine if it is an array  Echo"<br/>"; $arr 6=Array(23,56); $b=4; Echo Is_array($arr 6); Echo"<br/>".Is_array($b); //******************** splitting a string explode returning an array  $str= "Beijing & Shunping & Tianjin & Song Jiang"; $arr 7=Explode("&",$str); Echo"<br/>".Var_dump($arr 7)." Element has ".Count($arr 7); //Example  Echo"<br/>"; $colors=Array("Red", "Blue", "green", "yellow");  for($i= 0;$i<Count($colors);$i++) {    Echo"<br/>".$colors[$i]; } //using while traversal $i= 0;//Cyclic control Variables    while($i<Count($colors))    {        Echo"<br/>".$colors[$i]; $i++; }  // Do While $i=0; Do{   Echo"<br/>".$colors[$i]; $i++; } while($i<Count($colors)); //foreach Traversal foreach($colors  as $key=$val) {   Echo"<br>".$key." =".$val; } //**********unset releases a variable that uses the method to delete the element completely  $arr 8[0]=123; $arr 8[1]=345; $arr 8[2]= "Hello World"; unset($arr 8[1]); foreach($arr 8  as $val) {   Echo"<br/>".$val; } //If we create an array, we do not assign a subscript to an element,//Then PHP will use the current largest subscript value plus 1 as the subscript for that element. Echo"<br/>"; $arr=Array(5=> "logo", 567,90); $arr[5]= "yes";//Modifying the value of an array element can be modified directly by the index Echo $arr[5]; Echo"<br/>".$arr[6]; Echo"<br/>".$arr[7]; //Array Traps $arr[bar]= "Hello World";//No quotation marks are equivalent to bar being a constant, so that a fatal error may occur Echo"<br/>".$arr[bar];//array operator + means union two elements (will remove the same key on the right) $a=Array("A" and "Apple", "b" = "Bannana"); $b=Array("a" = "pear", "b" = "Strawberry", "C" and "Cherry"); $c=$a+$b; Echo"\ $a +\ $b result <br/>"; Var_dump($c); $c=$b+$a; Echo"\ $b +\ $a result <br/>"; Var_dump($c);?>

PHP Learning Note Nine "array two"