CODEWITHSUNDEEP
assembly6502
staworko
staworko

Reputation: 81

Difference between = and :=

I'm new to 6502 assembly programming and I'm using cc65 suite (with C64 being the target). The official documentation indicates that "The assembler accepts the standard 6502/65816 assembler syntax" however I have a hard time finding an authoritative reference. One thing I don't understand is the difference between the two assignment (?) operators in 6502 assembly "=" and ":=".

For instance in the file "c64.inc" we find 

BASIC_BUF       := $200         ; Location of command-line
BASIC_BUF_LEN   = 89            ; Maximum length of command-line

Upvotes: 4

Views: 245

Answers (2)

staworko
staworko

Reputation: 81

As @JoachimPileborg points out the cc65 documentation does explain it. The first operator = creates a symbol and assigns a given value to it. The second operator := also makes the symbol a label. The names and values of labels are exported as a part of debug information by the compiler (with the -g option), which is not the case with regular symbols. Consequently, it makes sense to use := to define memory locations and = for other purposes.

Upvotes: 4

Rakesh Jakhar
Rakesh Jakhar

Reputation: 6388

:= declares and assigns, = just assigns

:= is a short form for declaration and initialization. wheres = is an assignment operator, used in the same way as another programming language.

x := 12
y := "value"

x is declared as int and initialized with value 12 where y is declared as string and initialized with the value value

var x = 12
var y = "value"

Upvotes: 2

Related Questions