Tracing Variables in AS3 is not working

var a:Number;
var b:Number;

a + b = 17;

trace ("A: "a"       B: "b);

开发者_JS百科

Why does this not work? Is there somthing about tracing multiple pieces of information in the same trace statement in AS3?

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You have two issues in your code. The one the other answers apply to is the trace problem. The argument of a trace() call is any number of strings, separated by comma's. However, it is very common to just supply one and concatenate the string parts with the + sign.

trace("A: "+a+", B: "+b);

The real problem in your code however is a + b = 17, both in writing and in thinking. You cannot calculate the numeric outcome of an equation if you have more than one undetermined variable in there. A + B = C is only solvable in code if you know two of the three variables. If you want to write something moderately useful, try

var a:Number = 5;
var b:Number;

b = 12 - a;

trace("A: "+a+", B: "+b);

Apart from the math thinking, in code you're not writing math equations, you're writing assignment expressions. Whatever expression is to the right of the = sign, will get assigned to the variable to the left of the = sign. It will never work to assign one expression to two variables with an operator (+, *, -, /, %, etc) and hope that the math will magically resolve itself. a + b = something will never work, something = a + b might. In addition, trying to assign something to a constant and hoping it will resolve itself, like 12 = a + b, will also not work.

Cheers.

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You have to use the plus (+) symbol to concatenate strings together.

trace ("A: " + a + "B: " + b);

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In ActionScript 3, the trace method can take many parameters. But they must be comma seperated like any method call. So you could use:

trace ("A:", a, "B:", b);