PHP Operators and conditional tests and events

By the end of this pots you should be able to:

• Identify and apply logical, arithmetic and relational operators to scripts
• Apply an assignment operator

What are operators?

Operators are symbols that transform the value of a variable or form comparisons against them.

Here are some examples of arithmetic operators:

    $a = 42;
    $b = 20;
    
    $c = $a + $b;
    echo "Addition Operation Result: $c 
";
    $c = $a - $b;
    echo "Substraction Operation Result: $c 
";
    $c = $a * $b;
    echo "Multiplication Operation Result: $c 
";
    $c = $a / $b;
    echo "Division Operation Result: $c 
";
    $c = $a % $b;
    echo "Modulus Operation Result: $c 
";
    $c = $a++; 
    echo "Increment Operation Result: $c 
";
    $c = $a--; 
    echo "Decrement Operation Result: $c 
";

Source: php.net/manual/en/language.operators.arithmetic.php

Logical Operators

   //Test one:  If both have something in them the condition will be TRUE - else FALSE
    $a = 40;
    $b = 1;
    
    if( $a && $b ){
       echo "TEST1 : Both a and b are true
";
    }else{
       echo "TEST1 : Either a or b is false
";
    }
	//Here we are using the 'and' operator
   if( $a and $b ){
       echo "TEST2 : Both a and b are true
";
    }else{
       echo "TEST2 : Either a or b is false
";
    }
    

Source: php.net/manual/en/language.operators.logical.php

Note: the use of:

&&

and

and

. Both are valid though && is supposed carry more precedence. I suggest && is the preferred choice.

Comparison or Relational Operators

Comparison operators are similar to logic but this is about comparing values against one another rather than simply on/off.

 $a = 10;
 $b = 20;
	
	/*Ternary operators are if/else statements in shorthand*/
    
    /* If condition is true then assign a to result otheriwise b */
    $result = ($a > $b ) ? $a : $b;
    echo "TEST1 : Value of result is $result
";
    /* If condition is true then assign a to result otheriwise b */
    $result = ($a < $b ) ? $a : $b;
    echo "TEST2 : Value of result is $result
";
	
    /* most basic usage of ternary operators */
    $var = 5;
    $var_is_greater_than_two = ($var > 2 ? true : false); // returns true
	
   /*TIP: when learning how to use ternary operators write them in if/else first*/

Assignment Operators

In brief…

• Assignment operators assign a value to a variable
• Similar to arithmetic variables such as ++ or –
• They hold a variable with a value in memory and add additional value/s to it
• Assignment operators allow you to do complex calculations
• VAT and Non-VAT items for example

    $a = 42;
    $b = 20;
    
    $c = $a + $b;   /* Assignment operator */
    echo "Addition Operation Result: $c 
";
    $c += $a;  /* c value was 42 + 20 = 62 */
    echo "Add AND Assigment Operation Result: $c 
";
    $c -= $a; /* c value was 42 + 20 + 42 = 104 */
    echo "Subtract AND Assignment Operation Result: $c 
";
    $c *= $a; /* c value was 104 - 42 = 62 */
    echo "Multiply AND Assignment Operation Result: $c 
";
    $c /= $a;  /* c value was 62 * 42 = 2604 */
    echo "Division AND Assignment Operation Result: $c 
";
    $c %= $a; /* c value was 2604/42 = 62*/
    echo "Modulus AND Assignment Operation Result: $c 
";

Source: php.net/manual/en/language.operators.assignment.php

In this post we have explored…

• Identified and applied logical, arithmetic and relational operators to scripts
• Applied assignment operators and discussed where we might apply them