CODEWITHSUNDEEP
java
cobie
cobie

Reputation: 7281

Why do these two code fragments differ

I just noticed that when I change the last line in the code fragment from potential =+ rep_pot to potential = potential + rep_pot, I get completely different behaviour. Has anybody got any idea why this is happening?

double potential = euclideanDistance(i, goal);
for (IntPoint h: hits){
    double dist = euclideanDistance(i, h);
    double a = range - dist;
    double rep_pot = (Math.exp(-1/a)) / dist;
    potential =+ rep_pot;
}

Upvotes: 0

Views: 87

Answers (4)

Serge
Serge

Reputation: 6095

Yes, because these two things are not equivalent.

potential =+ rep_pot;

Here we have potential assigned a value of the expression 'unary plus rep_pot'

The thing you intendet to write looks differently:

potential += rep_pot;

And this is equivalent to 

potential = potential + rep_pot;

Upvotes: 1

giorashc
giorashc

Reputation: 13713

You probably meant +=. In your case it is interpreted as x = +x which is x = x

Use += :

potential += rep_pot;

Upvotes: 1

Peter Lawrey
Peter Lawrey

Reputation: 533880

That is because

potential = potential + rep_pot

is similar to

potential += rep_pot

and

potential =+ rep_pot;

is the same as

potential = rep_pot;

Upvotes: 1

user647772
user647772

Reputation:

There is no =+ operator in Java. See the Java Language Specification for all legal operators.

=+ are two operators: = followed by +.

Upvotes: 1

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