I’m not entirely sure what you’re asking, but I’ll try my best to answer. The following declares a variable i on the stack: int i; When I ask for an address using &i I get the actual location on the stack. When I allocate something dynamically using malloc, there are actually TWO pieces of data … Read more
I see three main problems with your code: Use of naked, owning pointers. Use of naked new. Use of dynamic arrays. Each is undesirable for its own reasons. I will try to explain each one in turn. (1) violates what I like to call subexpression-wise correctness, and (2) violates statement-wise correctness. The idea here is … Read more
This is actually a really hard, imponderable question. Pro (in favor of freeing everything before exit): no bugs or memory leaks later if code is rearranged no false positives from valgrind or memory leak checker no memory leaks if you’re running under a buggy OS, or no OS at all Con (just exit, don’t worry … Read more
The draft n4296 for C11 is explicit that pointing one past an array is perfecly defined: 6.5.6 Language / Expressions / Additive operators: ยง 8 When an expression that has integer type is added to or subtracted from a pointer, the result has the type of the pointer operand. … Moreover, if the expression P … Read more
TL;DR: yes, it is on the stack. The longer story: C++ has no concept of stack or heap. Those are implementation details, and there is at least one platform that does not use a traditional stack (but rather linked list of heap allocations for it). It has automatic storage and the free store. new accesses … Read more
In order to answer the question, we should first clear up some concepts. What is an array and how can it be used? And what is the code in the question, if not an array? What is an array? The formal definition of an array is found in the C standard, ISO 9899:2011 6.2.5/20 Types. … Read more
Setting a pointer to 0 (which is “null” in standard C++, the NULL define from C is somewhat different) avoids crashes on double deletes. Consider the following: Foo* foo = 0; // Sets the pointer to 0 (C++ NULL) delete foo; // Won’t do anything Whereas: Foo* foo = new Foo(); delete foo; // Deletes … Read more
If your row length is a compile time constant, C++11 allows auto arr2d = new int [nrows][CONSTANT]; See this answer. Compilers like gcc that allow variable-length arrays as an extension to C++ can use new as shown here to get fully runtime-variable array dimension functionality like C99 allows, but portable ISO C++ is limited to … Read more