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functions [2019/05/16 11:25]
neils
functions [2019/12/12 20:35] (current)
neils [Functions]
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 ====== Functions ====== ====== Functions ======
  
-**XC=BASIC** ​offers several built-in functions. In addition, you can use the [[USR|USR() function]] to call your own machine language function.+Functions in **XC=BASIC** ​are procedures that return a value of a certain type.
  
-===== Return type =====+**XC=BASIC** supports:
  
-Some functions may return miscellaneous types and you have to explicitly ​tell the compiler ​which type you require. Just like with variables, ​the return type of a function is denoted with a [[https://​en.wikipedia.org/​wiki/​Sigil_(computer_programming)|sigil]]. For example, the [[ABS|ABS function]] can return an integer or a float:+  * Several built-in functions 
 +  * The [[USR|USR() function]] to call a machine language function 
 +  * [[fun|User-defined functions]] (since version 2.2) 
 + 
 + 
 +===== Calling overloaded functions ===== 
 + 
 +Some of the built-in ​functions ​are overloaded and thus they may return ​values of miscellaneous types. When calling a function, ​you must explicitly ​specify ​which type you wish to call by appending ​the right [[https://​en.wikipedia.org/​wiki/​Sigil_(computer_programming)|sigil]] ​to the function name. For example, the [[ABS|ABS function]] can return an integer or a float:
  
   myInt = abs(-5)   myInt = abs(-5)
   myFloat%= abs%(-3.14)   myFloat%= abs%(-3.14)
  
-Another example is [[RND|RND]] that can return three types:+Another example is [[RND|RND]] that can return three different ​types:
  
   myRandomByte! ​ = rnd!()   myRandomByte! ​ = rnd!()
   myRandomInt ​   = rnd()   myRandomInt ​   = rnd()
   myRandomFloat% = rnd%()   myRandomFloat% = rnd%()
 +  ​
 +Note: user defined functions may not be overloaded.
 +===== Defining user functions =====  ​
 +
 +Please refer to the [[fun|FUN ... ENDFUN]] directive for details.