post-increment

I just started to study C, and when doing one example about passing pointer to pointer as a function's parameter, I found a problem. This is my sample code : #include <stdio.h> #include <string.h> #include <stdlib.h> int* allocateIntArray(int* ptr, int size){ if (ptr != NULL){ for (int i = 0; i < size; i++){ ptr[i] = i; } } return ptr; } void increasePointer(int** ptr){ if (ptr != NULL){ *ptr += 1; /* <----------------------------- This is line 16 */ } } int main() { int* p1 = (int*)malloc(sizeof(int)* 10); allocateIntArray(p1, 10); for (int i = 0; i < 10; i++){ printf("%d\n", p1[i]); }

Why does this int x = 2; for (int y =2; y>0;y--){ System.out.println(x + " "+ y + " "); x++; } prints the same as this? int x = 2; for (int y =2; y>0;--y){ System.out.println(x + " "+ y + " "); x++; } As far, as I understand a post-increment is first used "as it is" then incremented. Are pre-increment is first added and then used. Why this doesn't apply to the body of a for loop? The loop is equivalent to: int x = 2; { int y = 2; while (y > 0) { System.out.println(x + " "+ y + " "); x++; y--; // or --y; } } As you can see from reading that code, it doesn't matter whether you use the post or

Possible Duplicate: Undefined Behavior and Sequence Points Pleae explain the behaviour of following statements int b=3; cout<<b++*++b<<endl; How will it be calculated? Greg Howell The behavior here is undefined. See this question Relevant standard quote: §5/4.1 Between the previous and next sequence point a scalar object shall have its stored value modified at most once by the evaluation of an expression. The most common sequence point is the end of a statement. Also worth noting from the standard: §5.2.2/8 The order of evaluation of arguments is unspecified. The standard says this is

I have a question about these two C statements: x = y++; t = *ptr++; With statement 1, the initial value of y is copied into x then y is incremented. With statement 2, We look into the value pointed at by *ptr, putting that into variable t, then sometime later increment ptr. For statement 1, the suffix increment operator has higher precedence than the assignment operator. So shouldn't y be incremented first and then x is assigned to the incremented value of y? I'm not understanding operator precedence in these situations. You're mistaken about the meaning of your 2] . Post-increment always

The array.prototype.reduce function at: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce It has the following loop: for (index = 0; length > index; ++index) { if (this.hasOwnProperty(index)) { if (isValueSet) { value = callback(value, this[index], index, this); } else { value = this[index]; isValueSet = true; } } } I don't think there is a difference whether the index is pre or post incremented here since it's done after the loop iterates each time, but want to be certain. Can this be changed to index += 1 so it passes jslint? Please don't debate

I have an int pointer (i.e., int *count ) that I want to increment the integer being pointed at by using the ++ operator. I thought I would call: *count++; However, I am getting a build warning "expression result unused" . I can: call *count += 1; But, I would like to know how to use the ++ operator as well. Any ideas? Doug T. The ++ has equal precedence with the * and the associativity is right-to-left . See here. It's made even more complex because even though the ++ will be associated with the pointer the increment is applied after the statement's evaluation. The order things happen is: