If else statement in PHP:
If statement executes a statement or a group of statements if a specific condition is satisfied by the user expectation. When the condition gets false (fail) the else block is executed.
Syntax:
if (condition)
{
Execute statement(s) if condition is true;
}
else
{
Execute statement(s) if condition is false;
}
Example
＄Pass_Mark=35;
＄Student_Mark= 70;
if (＄Student_Mark>= ＄Pass_Mark){
echo "The Student is eligible for the promotion";
}
else {
echo "The Student is not eligible for the promotion";
} ?>

If elseif else statement in PHP:
If-elseif-else statement is a combination of if-else statement. More than one statement can execute the condition based on user needs.
Syntax:
if (1^st condition)
{
Execute statement(s) if condition is true;
}
elseif(2^nd condition)
{
Execute statement(s) if 2^nd condition is true;
}
else
{
Execute statement(s) if both conditions are false;
}
Example Program:
＄Pass_Mark=35;
＄first_class=60;
＄Student_Mark= 70;
if (＄Student_Mark > = ＄first_ class){
echo "The Student is eligible for the promotion with First Class";
}
elseif (＄Student_Mark >= ＄Pass_Mark){
echo "The Student is eligible for the promotion";
}
else {
echo "The Student is not eligible for the promotion";
} ?>

Conditional statements in PHP are implemented by the following types:
(i) if Statement
(ii) if... else Statement
(iii) if... elseif... else Statement
(iv) switch Statement
(i) If statement in PHP:
If statement executes a statement or a group of statements if a specific condition is satisfied as per the
user expectation.
Syntax:
if (condition)
{
Execute statement(s) if condition is true;
}
(ii) If else statement in PHP:
If statement executes a statement or a group of statements, if a specific condition is satisfied by the user
expectation. When the condition gets false (fail) the else block is executed.
Syntax:
if (condition)
{
Execute statement(s) if condition is true;
}
else
{
Execute statement(s) if condition is false;
(iii) If elseif else statement
It is a combination of if-else statement. More than one statement can execute the condition based on user needs.
Syntax:
if (1st condition)
{
Execute statement(s) if condition is true;
}
elseif (2nd condition)
{
Execute statement(s) if 2nd condition is true;
}
else
{
Execute statement(s) if both conditions are false;
}
(iv) Switch Statement
It is used to perform different actions based on different conditions.
Syntax:
switch (n) {
case label 1:
code to be executed if n-label1;
break;
case label2:
code to be executed if n=label2;
break;
***
default:
code to be executed if n is different from all labels;
}

Switch Statement:
(i) This is a multiple branching statement where, based on a condition, the control is transferred to one of the many possible points.
(ii) The switch statement is used to specify multiple conditions. It runs a different code block for different conditions.
Syntax
switch (expression)
{
case value1:
      //code to be executed if expression = value1; break;
case value2:
      //code to be executed if expression = value2; break;
...
default:
      //code to be executed if expression is not equal to any of the values;
}
Example:
    ＄x = 10;
     switch (＄x)
     {
          case 5:
               echo "x is equal to 5";
                break;
           case 10:
                echo "x is equal to 10";
                 break;
            case 15:
                 echo "x is equal to 15";
                  break;
             default:
                  echo "x is not equal to 5, 10, or 15";
           }
?>
Output:
x is equal to 10

(i) If statement in PHP: If statement executes a statement or a group of statements if a specific condition is satisfied as per the users expectation. This is the simplest PHP's conditional statement and can be written in the following form.
Syntax:
if (condition)
{
     // code to be executed if condition is true;
}
(ii) If else statement in PHP: The if statement evaluates a condition and executes a set of code if the condition is true and another set of code if the condition is false.
Syntax:
if(condition)
{
       //True-block;
}
else
{
       //False-block;
}
(iii) If-elseif-else statement in PHP: If-elseif-else statement is a combination of if-else statement. Here multiple conditions can be checked and action is based on the result of the condition.
Syntax:
if (Condition 1)
{
          //code to be executed if condition 1 is true;
}
elseif (condition2)
{
         //code to be executed if condition1 is false and condition2 is true;
}
elseif (condition3)
{
         // code to be executed if condition1 and condition2 are false and condition3 is true;
}
else
{
         //code to be executed if all conditions are false;
}
Switch case: The switch case is an alternative to the if.. elseif.. else statement which executes a block of code corresponding to the match.
Syntax:
switch (expression)
case value1:
           //code to be executed if expression= value1; break;
case value2;
           //code to beexecuted if expression = value2; break;
...
default:
           //code to be executed if cexpression is not equal to any of the values;
}