PHP Developer’s Dictionary IT-SC book 90 The == operator compares variable1 to variable2 to see whether they are equal. If they are, true is returned. === (Identical) Syntax variable1 === variable2 Description The === operator compares variable1 to variable2 to see whether they are identical and are of the same data type. If they are, true is returned. $num1 = 5; $num2 = 5; $string = "5"; $result1 = ($num1 === $num2); // returns 1 $result2 = ($num1 === $string); // returns 0 != (Not Equal) Syntax variable1 != variable2 Description The != operator compares variable1 to variable2 to see whether they are not equal. If they are not equal, true is returned. < (Less Than) Syntax variable1 < variable2 Description The < operator checks whether variable1 is less than variable2 . If so, true is returned. PHP Developer’s Dictionary IT-SC book 91 > (Greater Than) Syntax variable1 > variable2 Description The > operator checks whether variable1 is greater than variable2 . If so, true is returned. <= (Less Than or Equal) Syntax variable1 <= variable2 Description The <= operator checks whether variable1 is less than or equal to variable2 . If so, true is returned. $num1 = 5; $num2 = 4; $result = ($num1 <= $num2); // returns 0 >= (Greater Than or Equal) Syntax variable1 >= variable2 Description The >= operator checks to see if variable1 is greater than or equal to variable2 . If so, true is returned. Incrementing and Decrementing PHP Developer’s Dictionary IT-SC book 92 The incrementing and decrementing operators are used to increase or decrease the values of the items to which they are applied. This process can occur in a pre- or post- timeframe, and is most often used to increase or decrease counters, such as in loops. ++num (Pre-Increment) Syntax ++num Description The ++ num operator increases the value of num by one. If num =0 and ++ num is applied, num will now equal 1. Because the ++ operator is applied before num , the increase is applied before anything else. For instance, if you tried to print ++ num when num =0 , it would print 1 . This is the opposite of post-increment, where 0 would be printed and the value would be adjusted after the print statement. num (Pre-Decrement) Syntax num Description The num operator decreases the value of num by one. If num =1 and num is applied, num will now equal 0 . Because the operator is applied before num , the decrease is applied before anything else. For instance, if you tried to print num when num = 1 , it would print 0 . This is the opposite of post-decrement, where 1 would be printed and the value would be adjusted after the print statement. num++ (Post-Increment) Syntax num++ Description PHP Developer’s Dictionary IT-SC book 93 The num ++ operator increases the value of num by one. If num =0 and num ++ is applied, num will now equal 1 . Because the ++ operator is applied after num , the increase is applied after anything else. For instance, if you tried to print num ++ when num =0 , it would print 0 . This is the opposite of pre-increment, where 1 would be printed and the value would be adjusted before the print statement. num (Post-Decrement) Syntax num Description The num operator decreases the value of num by one. If num =1 and num is applied, num will now equal 0 . Because the operator is applied after num , the decrease is applied after anything else. For instance, if you tried to print num when num =1 , it would print 1 . This is the opposite of pre-decrement where 0 would be printed and the value would be adjusted before the print statement. Other Some groups of operators, such as error control, have only one language element in them. For organization reasons, we have included these items in this section of this chapter. @ (Error Control) Syntax @ expression Description The @ operator, which can be prepended to any PHP expression, tells the interpreter to ignore any error messages that it might encounter. Note Any errors that are encountered will be stored in the $php_errormsg variable if the track_errors option is set in the configuration file. If there is an error, this enables you to stop the program, access the error, and write it to the page. See the die() entry in Chapter 5, "PHP Language Extensions," for more information. PHP Developer’s Dictionary IT-SC book 94 ` ` (Execution) Syntax `command` Description The ` ` operator will attempt to execute the shell command . If you set a variable equal to this operator, the results of running command will be stored in the variable. Warning These are backticks, not single quotes. Logical Logical operators are very similar to comparison operators and are used to evaluate Boolean expressions. When using this type of operator, it is important to understand the corresponding truth tables. In this section of the chapter, we discuss these operators and each entry will contain its corresponding truth table. and Syntax variable1 and variable2 Description The and operator evaluates whether both variable1 and variable2 are true, or equal. Table 4.5 contains the truth table for the possible values. In understanding the truth table, you can see the only time the equation returns true is when both variable1 and variable2 are true. Note The only difference between this operator and the && operator is order precedence. . prepended to any PHP expression, tells the interpreter to ignore any error messages that it might encounter. Note Any errors that are encountered will be stored in the $php_ errormsg variable. and write it to the page. See the die() entry in Chapter 5, " ;PHP Language Extensions," for more information. PHP Developer’s Dictionary IT-SC book 94 ` ` (Execution) Syntax. greater than or equal to variable2 . If so, true is returned. Incrementing and Decrementing PHP Developer’s Dictionary IT-SC book 92 The incrementing and decrementing operators are used