allocation

问题 I have a MS-Visual Studio 2005 workspace having all c code. This application(exe) allocates memory dynamically from heap using malloc and realloc. I want to calculate the maximum size allocated size allocated on heap using malloc/realloc by this application program when i run particular test case. I do not want to change the code by noting the malloc sizes and accumulating them, because: a) there can be a scenario, that some memory of 1KB is malloc'ed, then freed, and then a memory of 2KB is

问题 The normal way to initialise and allocate in Objective-C is NSObject *someObject = [[NSObject alloc] init]; Why is the following not practised? NSObject *someObject = [NSObject alloc]; [someObject init]; 回答1: The main problem is that you might end up using the wrong object. init is special in many classes as it might just release the receiver and instead create a new object that resides at a different address. So your someObject then points to the wrong (uninitialized) instance. There are a

问题 Hi I am having difficulties in understanding about how the memory is allocated to the structure elements. For example if i have the below structure and the size of char is 1 and int is 4 bytes respectively. struct temp { char a; int b; }; I am aware that the size of the structure would be 8. Because there will be a padding of 3 bytes after the char, and the next element should be placed in multiple of 4 so the size will be 8. Now consider the below structure. struct temp { int a; // size is 4

问题 Hi I am having difficulties in understanding about how the memory is allocated to the structure elements. For example if i have the below structure and the size of char is 1 and int is 4 bytes respectively. struct temp { char a; int b; }; I am aware that the size of the structure would be 8. Because there will be a padding of 3 bytes after the char, and the next element should be placed in multiple of 4 so the size will be 8. Now consider the below structure. struct temp { int a; // size is 4

问题 This is something I've been wondering for a while and never found an answer for: Why is it that when you allocate something on the heap you cannot determine the size of it from just the pointer, yet you can delete it using just the pointer and somehow C++ knows how many bytes to free? Does this have something to do with the way it is stored on the heap? Is this information there but not exposed by C++? And perhaps this should be a separate question but I think it's pretty related so I'll ask

问题 This is something I've been wondering for a while and never found an answer for: Why is it that when you allocate something on the heap you cannot determine the size of it from just the pointer, yet you can delete it using just the pointer and somehow C++ knows how many bytes to free? Does this have something to do with the way it is stored on the heap? Is this information there but not exposed by C++? And perhaps this should be a separate question but I think it's pretty related so I'll ask

问题 I'm trying to decide which one of these two options would be the best: subroutine sqtrace( Msize, Matrix, Value ) integer, intent(in) :: Msize real*8, intent(in) :: Matrix(Msize, Msize) real*8, intent(out) :: Value [instructions...] end subroutine sqtrace VS subroutine sqtrace( Matrix, Value ) real*8, intent(in) :: Matrix(:,:) real*8, intent(out) :: Value if ( size(Matrix,1) /= size(Matrix,2) ) then [error case instructions] end if [instructions...] end subroutine sqtrace I understand that

问题 I just starting to learning vectors and little confused about size() and capacity() I know little about both of them. But why in this program both are different? even array(10) is making room for 10 elements and initializing with 0. Before adding array.push_back(5) So array.size(); is 10 that is ok. So array.capacity(); is 10 that is ok. After adding array.push_back(5) So array.size(); is 11 that is ok (already 10 time 0 is added and then push_back add one more element 5 ) . So array.capacity

问题 I just starting to learning vectors and little confused about size() and capacity() I know little about both of them. But why in this program both are different? even array(10) is making room for 10 elements and initializing with 0. Before adding array.push_back(5) So array.size(); is 10 that is ok. So array.capacity(); is 10 that is ok. After adding array.push_back(5) So array.size(); is 11 that is ok (already 10 time 0 is added and then push_back add one more element 5 ) . So array.capacity

问题 I am looking for a good memory pool implementation in C. it should include the following: Anti fragmentation. Be super fast :) Ability to "bundle" several allocations from different sizes under some identifier and delete all the allocations with the given identifier. Thread safe 回答1: I think the excellent talloc, developed as part of samba might be what you're looking for. The part I find most interesting is that any pointer returned from talloc is a valid memory context. Their example is: