Assignment Operations
There are two assignment operations in BR: the equal sign =, which denotes regular assignment, and the colon-equal sign :=, which denotes forced assignment,
They are similar in how they work with a slight difference.
Both of them are Binary operations, which means they take two arguments - one on the left side of the operator, and another one on the right and both may be used with Numeric and String variables.
Regular Assignment
The equal sign = simply makes the variable on the left side of it equal to the value on the right side of it. The example below assigns the value of 5 to the variable x:
00010 let x = 5 ! correct
Note that you cannot do the reverse. The example below will result in an error.
00010 let 5 = x ! incorrect
Forced Assignment
The example below forced-assigns the value of 5 to x and then compares the value of x (which is now 5) to the value of 2:
00010 if (x:=5) > 2 then print "The forced-assigned value is larger than 2"
Note that when this assignment operation is used in any expression (for example: in the condition of an IF THEN statement), parentheses must be used to clarify the order of execution Otherwise, unexpected results may occur.
IMPORTANT NOTE: when the equal sign is used in an IF Statement, it is NOT used for assignment. Instead, it is used for comparison. Consider the example below:
00010 let x = 1 ! assignment takes place 00020 let y = 1000 ! assignment takes place 00030 if x = y then print "1 is equal to 1000" ! assignment DOES NOT takes place
In the above example, assignment DOES NOT takes place, instead the IF statement evaluates to FALSE and the print statement DOES NOT execute.
IMPORTANT NOTE: when the equal sign is used in an IF Statement, it is equivalent to using two equal signs ==. So the above example is identical in effect to the one below:
00010 let x = 1 ! assignment takes place 00020 let y = 1000 ! assignment takes place 00030 if x == y then print "1 is equal to 1000" ! assignment DOES NOT takes place
For clarity, it may be better to use == for comparison.
IMPORTANT NOTE: when the forced assignment operation := is used in an IF Statement, it is used for forced assignment, not for comparison. Consider the example below:
00010 let x = 1 00020 if x:=2 then print "forced assignment as a condition of an if statement always evaluates to true"