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C++ new int[0] — will it allocate memory?
... When the value of the expression in a direct-new-declarator is zero, the allocation function is called to allocate an array with no elements.
From 3.7.3.1/2
The effect of dereferencing a pointer returned as a request for zero size is undefined.
Also
Even if the size of the space reques...
STL中map容器使用自定义key类型报错详解 - C/C++ - 清泛网 - 专注C/C++及内核技术
...对正在编译的类 模板 实例化“std::_Tmap_traits<_Kty,_Ty,_Pr,_Alloc,_Mfl>”的引用
1> with
1> [
1> _Kty=a,
1> _Ty=int,
1> _Pr=std::less<a>,
1> _Alloc=std::allocator<std::pair<const a,int>>,
1> _Mf...
What's the Hi/Lo algorithm?
...erability with other 3rd-party clients that are not aware of this sequence allocation strategy.
Being both efficient and interoperable with other systems, the pooled-lo optimizer is a much better candidate than the legacy hi/lo identifier strategy.
...
When vectors are allocated, do they use memory on the heap or the stack?
...
vector<Type> vect;
will allocate the vector, i.e. the header info, on the stack, but the elements on the free store ("heap").
vector<Type> *vect = new vector<Type>;
allocates everything on the free store.
vector<Type*> vect;
...
Why malloc+memset is slower than calloc?
It's known that calloc is different than malloc in that it initializes the memory allocated. With calloc , the memory is set to zero. With malloc , the memory is not cleared.
...
How to add 2 buttons into the UINavigationbar on the right side without IB?
...ith iOS 5+ it's as easy as:
UIBarButtonItem *btnShare = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAction target:self action:@selector(share)];
UIBarButtonItem *btnRefresh = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemRefresh target:self ...
What is the meaning of the term arena in relation to memory?
...
An arena is just a large, contiguous piece of memory that you allocate once and then use to manage memory manually by handing out parts of that memory. For example:
char * arena = malloc(HUGE_NUMBER);
unsigned int current = 0;
void * my_malloc(size_t n) { current += n; return arena +...
Stack, Static, and Heap in C++
...t understood very well these three concepts. When do I have to use dynamic allocation (in the heap) and what's its real advantage? What are the problems of static and stack? Could I write an entire application without allocating variables in the heap?
...
Difference between malloc and calloc?
...
calloc() gives you a zero-initialized buffer, while malloc() leaves the memory uninitialized.
For large allocations, most calloc implementations under mainstream OSes will get known-zeroed pages from the OS (e.g. via POSIX mm...
How to create fixed space and flexible space bar button items programmatically?
...
UIBarButtonItem *fixedItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFixedSpace target:nil action:nil];
fixedItem.width = 20.0f; // or whatever you want
UIBarButtonItem *flexibleItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem...