post-increment

问题 I am confused about the post ++ and pre ++ operator , for example in the following code int x = 10; x = x++; sysout(x); will print 10 ? It prints 10,but I expected it should print 11 but when I do x = ++x; instead of x = x++; it will print eleven as I expected , so why does x = x++; doesn't change the the value of x ? 回答1: No, the printout of 10 is correct. The key to understanding the reason behind the result is the difference between pre-increment ++x and post-increment x++ compound

问题 This question already has an answer here: How do the post increment (i++) and pre increment (++i) operators work in Java? 14 answers In programming, particularly in Java, what is the difference between: int var = 0; var++; and int var = 0; ++var; What repercussions would this have on a for loop? e.g. for (int i = 0; i < 10; i++) {} for (int i = 0; i < 10; ++i) {} 回答1: tldr; Although both var++ and ++var increment the variable they are applied to, the result returned by var++ is the value of

问题 I\'m doing some research about Java and find this very confusing: for (int i = 0; i < 10; i = i++) { System.err.print(\"hoo... \"); } This is never ending loop! Anybody has good explanation why such thing happens? 回答1: for (int i = 0; i < 10; i = i++) { The above loop is essentially the same as: - for (int i = 0; i < 10; i = i) { the 3 rd part of your for statement - i = i++ , is evaluated as: - int oldValue = i; i = i + 1; i = oldValue; // 3rd Step You need to remove the assignment from

问题 My interest is in the difference between for and while loops. I know that the post-increment value is used and then incremented and the operation returns a constant pre-increment. while (true) { //... i++; int j = i; } Here, will j contain the old i or the post-incremented i at the end of the loop? 回答1: Since the statement i++ ends at the ; in your example, it makes no difference whether you use pre- or post-increment. The difference arises when you utilize the result: int j = i++; // i will

问题 I am a little confused about how the C# compiler handles pre- and post increments and decrements. When I code the following: int x = 4; x = x++ + ++x; x will have the value 10 afterwards. I think this is because the pre-increment sets x to 5 , which makes it 5+5 which evaluates to 10 . Then the post-increment will update x to 6 , but this value will not be used because then 10 will be assigned to x . But when I code: int x = 4; x = x-- - --x; then x will be 2 afterwards. Can anyone explain

问题 I\'m trying to get deeper with post and pre incrementors but am a bit stuck with the following expression : public static void main(String[] args) { int i = 0; i = i+=(++i + (i+=2 + --i) - ++i); // i = 0 + (++i + (i+=2 + --i) - ++i); // i = 0 + (1 + (3 + 2) - 1); // i = 0 + (6 - 1); System.out.println(i); // Prints 0 instead of 5 } I know I\'m missing the logic somewhere but where? What I\'ve tried : Going from left to right (though I know it is not recommended) Going from the insidest

问题 This question already has answers here : Why are these constructs using pre and post-increment undefined behavior? (14 answers) Closed last year . I have some C code: main() { int a=1; void xyz(int,int); xyz(++a,a++); //which Unary Operator is executed first, ++a or a++? printf(\"%d\",a); } void xyz(int x,int y) { printf(\"\\n%d %d\",x,y); } The function xyz has two parameters passed in, ++a and a++ . Can someone explain the sequence of operations to explain the result? The above code prints

问题 I can\'t make heads or tails of the following code from \"java puzzlers\" by joshua bloch. public class Test22{ public static void main(String args[]){ int j=0; for(int i=0;i<100;i++){ j=j++; } System.out.println(j); //prints 0 int a=0,b=0; a=b++; System.out.println(a); System.out.println(b); //prints 1 } } I can\'t get the part where j prints 0. According to the author, j=j++ is similar to temp=j; j=j+1; j=temp; But a=b++ makes b 1. So it should\'ve evaluated like this, a=b b=b+1 By

问题 Is there a difference in ++i and i++ in a for loop? Is it simply a syntax thing? 回答1: a++ is known as postfix. add 1 to a, returns the old value. ++a is known as prefix. add 1 to a, returns the new value. C#: string[] items = {"a","b","c","d"}; int i = 0; foreach (string item in items) { Console.WriteLine(++i); } Console.WriteLine(""); i = 0; foreach (string item in items) { Console.WriteLine(i++); } Output: 1 2 3 4 0 1 2 3 foreach and while loops depend on which increment type you use. With

问题 I\'m currently learning C++ and I\'ve learned about the incrementation a while ago. I know that you can use \"++x\" to make the incrementation before and \"x++\" to do it after. Still, I really don\'t know when to use either of the two... I\'ve never really used \"++x\" and things always worked fine so far - so, when should I use it? Example: In a for loop, when is it preferable to use \"++x\"? Also, could someone explain exactly how the different incrementations (or decrementations) work? I