4.15. Lua if…else statement

4.15.1. If…else statement #

Lua if statement can be associated with the else statement is usedtogether, in if conditional expression is false , when the execution else statement code block.

Lua if...else syntax format of the statement is as follows:

if(Booleans) then --[Execute the statement block when the Boolean expression is true--] else --[Execute the statement block when the Boolean expression is false--] end 

When the Boolean expression is true at that time, if block of code in is executed when the Boolean expression is false , The code block for else will be executed.

Lua believes that false and nil are false, true and non nil are true. It should be noted that in Lua 0 for true .

The flow chart of the if statement is as follows:

4.15.2. Example #

The following example is used to determine a variable a value:

--[Define variables--] a = 100; --[Check Condition--] if( a < 20 ) then --[Execute the statement block when the if condition is true--] print("A less than 20" ) else --[Execute the statement block when the if condition is false--] print("A greater than 20" ) end print("The value of a is:", a) 

A greater than 20 The value of a is: 100 

4.15.3. If…else statement #

Lua if statement can be associated with the else statement is usedtogether, in if conditional expression is false when the execution else statement code block to detect multiple conditional statements.

Lua if...else syntax format of the statement is as follows:

if(Boolean expression 1) then --[Execute this statement block when Boolean expression 1 is true--] elseif(Boolean expression 2) then --[Execute this statement block when Boolean expression 2 is true--] elseif(Boolean Expression 3) then --[Execute this statement block when Boolean expression 3 is true--] else --[If none of the above Boolean expressions are true, execute the statement block--] end 

4.15.4. Example #

The following example sets the variable a to judge the value:

--[Define variables--] a = 100 --[Check Boolean conditions--] if( a == 10 ) then --[If the condition is true, print the following information--] print("The value of a is 10" ) elseif( a == 20 ) then --[Print the following information when the if else if condition is true--] print("The value of a is 20" ) elseif( a == 30 ) then --[If else if the condition is true, print the following information--] print("The value of a is 30" ) else --[Print the following information when none of the above conditional statements are true--] print("No matching value for a" ) end print("The true value of a is: ", a ) 

No matching value for a The true value of a is: 100