Why is the answer 5 and not 6

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1.00/5 (2 votes)

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int a=5;
int a=a++ ;
System.out.println(a);
the answer is 5 and not 6.can someone explain the logic of use and change operator

What I have tried:

i thought it was 6 but it seems to be 5

Posted 19-Mar-18 3:56am

Member 13734508

Updated 19-Mar-18 4:14am

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Richard Deeming 19-Mar-18 10:08am

The answer is "compiler error" - you can't have two variables with the same name.

2 solutions

Solution 2

The compiler uses an internal temporary variable when processing the postfix increment. If you extend the code by using an additional variable like the compiler does you can see why it happens:

Java

int a = 5;
// int temp = a++;
// is the same as
int temp = a;
a = a + 1;
// Finally the value of the temp variable is assigned
a = temp;

Posted 19-Mar-18 4:16am

Jochen Arndt

Comments

Maciej Los 19-Mar-18 10:21am

5!

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Richard Deeming · Accepted Answer · 2018-03-19T04:13:00

Assuming the duplicated variable name is a typo in your question, the explanation is in the documentation:

Assignment, Arithmetic, and Unary Operators (The Java™ Tutorials > Learning the Java Language > Language Basics)[^]:
The increment/decrement operators can be applied before (prefix) or after (postfix) the operand. The code result++; and ++result; will both end in result being incremented by one. The only difference is that the prefix version (++result) evaluates to the incremented value, whereas the postfix version (result++) evaluates to the original value. If you are just performing a simple increment/decrement, it doesn't really matter which version you choose. But if you use this operator in part of a larger expression, the one that you choose may make a significant difference.