pre-increment

问题 Does spaces have any meaning in these expressions: assume: int a = 1; int b = 2; 1) int c = a++ +b; Or, 2) int c = a+ ++b; When I run these two in visual studio, I get different results. Is that the correct behavior, and what does the spec says? In general, what should be evaluated first, post-increment or pre-increment? Edit: I should say that c =a+++b; Does not compile on visual studio. But I think it should. The postfix++ seems to be evaluated first. 回答1: Is that the correct behavior Yes,

问题 I had come across this answer to this question. In one of the line, the author mention's: In any case, follow the guideline "prefer ++i over i++ " and you won't go wrong. I know that ++i is slightly faster than i++ , but thought that there is no reason for them to go wrong. I searched for a while, and the closest I could get to was this. It explained clearly that why is it preferred to use ++i , but not still how could you go wrong using i++ . So can anyone tell me how can i++ go wrong? NOTE:

问题 This question already has answers here : Why are these constructs using pre and post-increment undefined behavior? (14 answers) printf(“%d %d %d\n”,++a, a++,a) output [duplicate] (3 answers) Closed 2 years ago . If n has the value 5 then output: printf("%d %d", n++, ++n); //should be 5 and 7 But I get as output 6 and 7. 回答1: Multiple unsequenced modifications result to such kind of Undefined Behavior . There are tons of results if you search for it, e.g. this question. Next time compile with

问题 I am really new to programming (I'm an electronics and comm. engineer) and I am not able to figure out why one program works and the other one doesn't. I'd like to get a good understanding of recursive functions before going any further with my learning. I would appreciate any help regarding this. I know the difference between the x++ and --x. But in this context of this program, I thought both of these programs should run the same way. But they don't. void rec(int x) { if(x>0) rec(x--);

问题 I'm working through K&R and am presently on Exercise 1-16. It occurs to me that thus far only pre-increment has been used in the book. Most other tutorial books and indeed source code I've seen tend to favour post-increment, except where there is an obvious affect such as in while loops etc. Is this a stylistic or technical consideration on the part of K&R? Or do I just need to be further through the book to get my answer?! 回答1: There are several aspects to this. Semantics The semantics of

问题 This question already has answers here : Is ++i really faster than i++ in for-loops in java? (11 answers) Closed 6 years ago . Is it more performant to do a pre-increment vs a post-increment in a for loop in java ? Sample code : for (int i=0; i<10; i++) and for (int i=0; i<10; ++i) I notice that when i do a pre-increment, the execution time is lesser that when i do the post-increment. Any suggestions on why this might be the case ? thanks. 回答1: I compiled a minimal example (Oracle jdk1.7.0_07

问题 Help me to resolve this please. The steps that follows that expressions are: //Expression offSpring1[m1++] = temp1; //Steps: 1.- increment m1 2.- assign temp1 to offSpring I have always thought that the expression inside the brackets was the first to be done. But now I am confuse. So if a write this: //Expression offSpring1[++m1] = temp1; //Steps would be: 1.- assign temp1 to offSpring 2.- increment m1 If the steps would be the same as first ones, what is the difference between i++ and ++i?

问题 int z = 1; System.out.println(z++ == ++z); System.out.println(++z == z++); the output will be: false true and I don't get why, please explain this to me. 回答1: First You Should Clear About Pre Increment & Post Increment Lets Have A Look int i=1; int j=i++; int k=++i; here in the value of j will be 1 and k will be 3 why means in i++ first store the value i into j and after which increments the value of i so j=1,i=2 ok :) now in the case of ++i where first increment the value and after that

问题 Say you have a recursive method, and you post-increment/decrement a value in the recursive call. Why will this result in a stack overflow exception when a pre-increment/decrement will not? Ex. numberCount(currentNumber++); //Stack overflow exception numberCount(++currentNumber); //No stack overflow exception Thanks in advance for any clarification. 回答1: The first numberCount(currentNumber++); //Stack overflow exception is equivalent to: numberCount(currentNumber); currentNumber += 1; while

问题 I'm having trouble understanding how Post Increment ( ++ ), Pre Increment ( -- ) and addition/subtraction work together in an example. x++ means add 1 to the variable. x-- means subtract 1 from the variable. But I am confused with this example: int x = 2, y = 3, z = 1;` y++ + z-- + x++; I assume this means 3(+1) + 1(-1) + 2(+1) Which means the result should be 7. But when I compile it, I get 6 . I don't understand. int main() { int x=2, y=3, z=1; int result; result = y++ + z-- + x++; //this