Front-end learning of PHP statements

Table of Contents [1] Conditional statement IF statement switch statement [2] loop statement while loop Do...while loop for loop foreach Loop condition statement

For performing different actions based on different conditions

If statement

if code executed when (  condition) {true ;}

if (condition) {  trueElse  {  false  when executing code;}

 if   (condition) {condition =  true   true   code executed;}  else   false   

<? PHP $t=date("H"); if ($t< "ten") {  echo "has a good morning!"  ElseIf ($t< ")  {echo " has a good day! "  Else  {  echo "has a good night!" ;}? >

Switch statement

 switch   case  label1: code to be executed  if   expression = Label1;   break  ;  case  label2: code to be executed  Span style= "color: #0000ff;"  >if  expression = Label2;  break   default :  code to be executed  if   expression is different from both Label1 and Label2;}  

 <? php  switch  ( $x    1: echo  "Number 1" ;  break   case  2: echo  "Number 2" ;  break   case  3: echo  "Number 3" ;  break   default : echo  "No number between 1 and 3" Span style= "color: #000000;" >;}? 

Looping statements

When writing code, you often need to run the same block of code repeatedly, and you can use loops to perform such tasks

While loop

 while {The condition is true) {  the code to execute;}

<?PHP$sum= 12;//the current level of hunger for small petsEcho"I'm hungry,:-(.";Echo"<br/>"; while($sum<100){//the small pet's hunger level to 100, indicates that the small pet eats the full, does not have to continue to feed, does not have the satiety to continue to feed    $num=Rand(1,20);//random numbers, simulating small-pet-fed buns  $sum=$sum+$num;//Small pets eat small bread  Echo"I haven't eaten enough yet!" "; Echo"<br/>";}Echo"I'm finally fed up, ^_^".;?>

Do...while Cycle

The loop executes the code block first, then checks the condition and repeats the loop if the specified condition is true

 Do {  while (condition is true);

<? PHP   $sum  = 0;     Do {    $numrand(1,6);   Gets the random number from 1 to 6, simulates the dice    $sum$sum  $num;   forward step  }while ($num==6);   Echo "The Do...while example executes and goes forward:". $sum . " <br/> ";? >

For loop

For loop statements, initialization is evaluated unconditionally before the start of the loop, and the loop condition is evaluated before each cycle begins. If the value is true, the loop is resumed, the loop body statement is executed, and if the value is False, the loop is terminated. Increment statements are executed after each loop

 for (init counter; test counter; increment counter) {  code to be executed;}    

<?   for ($x$x$x+ +)  {echo "number is:$x <br> "?>

foreach Loop

The Foreach loop applies only to arrays, which iterate through each key/value pair in the array. For each iteration of the loop, the value of the current array element is assigned to the $value variable, and the array pointer moves one at a time until the last array element is reached. Generally there are two ways: Do not remove the label, remove the

[1] Only value, do not remove the mark

foreach ($arrayas$value) {code to be  executed;}    

<?  $colorsarray("Red", "green", "blue", "yellow"foreach ($ Colorsas$value) {  echo "$value <br>"  ;}? >

[2] Simultaneously remove the mark and value

 foreach  ( $array  as   $index  =  $value  ) {code to be executed;} 

<?  $colorsarray(  "r" = "Red",  "g" = "green",  "b" = "Blue",  "Y" = "yellow"foreach ($colorsas$key$value {  echo$key. ":". ) $value. " <br> ";}? >

Front-end learning of PHP statements