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Scope of Global and Local variables in Allegro SKILL

JuanCR 5 months ago

By default, all variables in Allegro SKILL are global. Their value is accessible at any time and anywhere within your SKILL Code.

The use of global variables in SKILL, as with any language, should be kept to a minimum.

Global variables in SKILL

For example, in the code snippet given below, x1 and x2 become global variables by default. You can also access them from within a procedure.

x1 = 5

x2 = 10

procedure( update_vars(number1 number2)

printf("Inside proc:\t x1 is %d\t x2 is %d\t sum is %d\n" x1 x2 x1+x2)

x1 = number1

x2 = number2

)

printf("Before sum:\t x1 is %d\t x2 is %d \n" x1 x2)

update_vars(50 100)

printf("After sum: \t x1 is %d\t x2 is %d \n" x1 x2)

The result is:

Defining local variables

You can define local variables by using let or prog.

x1 = 5

x2 = 10

procedure( Local_Sum(number1 number2)
let( (x1 x2); notice we're intentionally using the same variable names
  x1 = number1
    x2 = number2
    printf("Inside Local_Sum:\t x1 is %d\t x2 is %d\t sum is is %d\n" x1 x2 x1+x2)
)
)

printf("Before Local_Sum:\t x1 is %d\t x2 is %d\t sum is is %d\n" x1 x2 x1+x2)
Local_Sum(1 2)
printf("After Local_Sum:\t x1 is %d\t x2 is %d\t sum is is %d\n" x1 x2 x1+x2)

The result is:

Interesting, isn't it? Play with the code snippets and let us know if you have any questions!

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