CODEWITHSUNDEEP
java
vkosyj
vkosyj

Reputation: 777

short term for incrementing in java

I am quite confused if there any difference the two below. I think they are doing the same thing but when I compile it seems like they are different. Thank you in advance. 

if(hash[s.charAt(leftIdx)]>=0) {
    hash[s.charAt(leftIdx)]++;    
    // do other things        
}

if(hash[s.charAt(leftIdx)]++>=0) {
    // do other things        
}

Upvotes: 0

Views: 56

Answers (1)

tavnab
tavnab

Reputation: 2734

Refactoring to remove the postfix operators, the first one is equivalent to this:

if(hash[s.charAt(leftIdx)] >= 0) {
    hash[s.charAt(leftIdx)] += 1;    
    // do other things
}

The second (assuming your hash members are integers) is equivalent to this:

int tmp = hash[s.charAt(leftIdx)];
hash[s.charAt(leftIdx)] += 1;
if(tmp >= 0) {
    // do other things
}

The postfix ++ operator returns the pre-incremented value and then increments it as a side-effect. So your if in the 2nd example is using the pre-incremented value in its condition (represented by tmp above).

Upvotes: 2

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