malloc

问题 I'm trying to free up the memory I've allocated with malloc , but the free command doesn't seem to do its job properly according to Eclipse's debugger. How's this possible? Below is a screenshot of my debugger after it supposedly freed up seCurrent->student->year , which is clearly not the case. year was allocated using malloc . alt text http://img693.imageshack.us/img693/7840/codeo.png 回答1: free() does not normally change any values in your program - it just makes adjustments to the C

问题 This question already has answers here : size of a pointer allocated by malloc [duplicate] (4 answers) Closed 6 years ago . I'm trying to create a pointer to a 6 element int in a function to return it later, so for that purpose I'm using malloc , but it seems to be acting not as I expected. Here's the code: int j = 0; for (;j < 5; j++) { int * intBig = malloc(j * sizeof(int)); printf("sizeof intBig - %ld\n", sizeof(intBig)); } Prints the same number 8 bytes as the sizeof(intBig) at each

问题 int getmin(int a, int b) { return a<b?a:b; } void *reallocation(void *ptr, size_t size) //size_t in bytes { void *newptr; int msize; msize = getsize(ptr); msize = getmin(msize, size); printf("msize = %d", msize); newptr = malloc(size); newptr = memcpy(newptr, ptr, msize); free(ptr); return newptr; } I have implemented my own realloc, and in order to get the size of the allocated memory using malloc(however i know there isn't any method for this in c). My reallocation function is working fine

问题 I am having a problem understanding how C allocates space for a 2D (or more dimensional) array, especially when we use malloc and the like. Take the program in this question for example. A one-dimensional array of pointers is first defined, then pointers to arrays of 1D data (in this case strings) are put in each one of boxes of the first 1D array. So there is no guarantee that the whole 2D array is contiguous (the last cell of the previous row is followed by the first cell of the next row).

问题 i just need to alloc memory & set values there.Here is my code. let radius:Float = 5.79 let sigma:Float = radius / 2 let size:Int = Int((round(radius) * 2) + 1) var weights:UnsafeMutableRawPointer = malloc(MemoryLayout<Float>.size * size * size) weights[some index] = some vale but I am getting an error message in swift version 4 saying "UnsafeMutableRawPointer has no subscript members" How can I fixed this.Any ideas please 回答1: You should better check the official documentation of

问题 Yes, I am taking a Computer systems course. I had a few questions about the various allocation schemes to implement malloc. For explicit lists, if I implement malloc using a LIFO-like stack, what exactly is the purpose of having pointers to previous freed memory? Like why do you need doubly-linked lists? Wouldn't singly linked lists work just as well? Malloc lecture. I found this link online, you can look at slide 7 to see what I'm talking about. When looking at a segregated list allocation

问题 Recently, I made a new friend. His name is _expand, and we've had some nice conversations, and I've even hung out with him a few times. But when I started asking around, no one had ever heard of my _expand. I became suspicious. I called a few thoroughly non-metaphorical friends at microsoft, and a few friends elsewhere in the business. Nothing. No one had ever used it. I noodled around various search engines and source trees. Nothing except a cursory mention here and there. Certainly not

问题 Relating to a previous question of mine I've successfully interposed malloc , but calloc seems to be more problematic. That is with certain hosts, calloc gets stuck in an infinite loop with a possible internal calloc call inside dlsym . However, a basic test host does not exhibit this behaviour, but my system's "ls" command does. Here's my code: // build with: g++ -O2 -Wall -fPIC -ldl -o libnano.so -shared Main.cc #include <stdio.h> #include <dlfcn.h> bool gNanoUp = false;// global //

问题 I have been taught in lectures, that calling free() on a pointer twice is really, really bad. I know that it is good practice, to set a pointer to NULL , right after having freed it. However, I still have never heard any explanation as to why that is. From what I understand, the way malloc() works, it should technically keep track of the pointers it has allocated and given you to use. So why does it not know, whether a pointer it receives through free() has been freed yet or not? I would love

问题 I have been taught in lectures, that calling free() on a pointer twice is really, really bad. I know that it is good practice, to set a pointer to NULL , right after having freed it. However, I still have never heard any explanation as to why that is. From what I understand, the way malloc() works, it should technically keep track of the pointers it has allocated and given you to use. So why does it not know, whether a pointer it receives through free() has been freed yet or not? I would love