Functions - Second Style¶
In this chapter we are going to learn about the next topics :-
Define functions
Call functions
Declare parameters
Send parameters
Main Function
Variables Scope
Return Value
Recursion
Define Functions¶
To define new function
Syntax:
def <function_name> [parameters]
Block of statements
[end]
Note
the keyword ‘end’ is optional.
Example:
def hello
put "Hello from function" + nl
end
Call Functions¶
To call function without parameters, we type the function name then ()
Tip
We can call the function before the function definition and the function code.
Example:
hello()
def hello
put "Hello from function" + nl
end
Example:
first() second()
def first put "message from the first function" + nl
def second put "message from the second function" + nl
Declare parameters¶
To declare the function parameters, after the function name type the list of parameters as a group of identifiers separated by comma.
Example:
def sum x,y
put x+y+nl
end
Send Parameters¶
To send parameters to function, type the parameters inside () after the function name
Syntax:
funcname(parameters)
Example:
/* output
** 8
** 3000
*/
sum(3,5) sum(1000,2000)
def sum x,y put x+y+nl
Main Function¶
Using the Ring programming language, the Main Function is optional, when it’s defined, it will be executed after the end of other statements.
if no other statements comes alone, the main function will be the first entry point
Example:
# this program will print the hello world message first then execute the main function
put "Hello World!" + nl
def main
put "Message from the main function" + nl
end
Variables Scope¶
The Ring programming language uses lexical scoping to determine the scope of a variable.
Variables defined inside functions (including function parameters) are local variables. Variables defined outside functions (before any function) are global variables.
Inside any function we can access the variables defined inside this function beside the global variables.
Example:
# the program will print numbers from 10 to 1
x = 10 # x is a global variable.
def main
for t = 1 to 10 # t is a local variable
mycounter() # call function
end
end
def mycounter
put x + nl # print the global variable value
x-- # decrement
end
Note
Using the main function before the for loop declare the t variable as a local variable, It’s recommended to use the main functions instead of typing the instructions directly to set the scope of the new variables to local.
Return Value¶
The function can return a value using the Return command.
Syntax:
Return [Expression]
Tip
the Expression after the return command is optional and we can use the return command to end the function execution without returning any value.
Note
if the function doesn’t return explicit value, it will return NULL (empty string = “” ).
Example:
if novalue() = NULL
put "the function doesn't return a value" + nl
end
def novalue