I’ve used tcmalloc and read about Hoard. Both have similar implementations and both achieve roughly linear performance scaling with respect to the number of threads/CPUs (according to the graphs on their respective sites). So: if performance is really that incredibly crucial, then do performance/load testing. Otherwise, just roll a dice and pick one of the … Read more
From http://www.gnu.org/s/libc/manual/html_node/Heap-Consistency-Checking.html#Heap-Consistency-Checking: Another possibility to check for and guard against bugs in the use of malloc, realloc and free is to set the environment variable MALLOC_CHECK_. When MALLOC_CHECK_ is set, a special (less efficient) implementation is used which is designed to be tolerant against simple errors, such as double calls of free with the same … Read more
You want to modify the value of an int* (your array) so need to pass a pointer to it into your increase function: void increase(int** data) { *data = realloc(*data, 5 * sizeof int); } Calling code would then look like: int *data = malloc(4 * sizeof *data); /* do stuff with data */ increase(&data); … Read more
It’s in stdlib.h (C) and cstdlib (C++). In general, for such questions, just try to look on google: “c++ function”. Most often the first hit will point to cplusplus.com for me containing a complete reference to the standard stuff.
After trying some things, I finally managed to figure out how to do this. First of all, in glibc, malloc is defined as a weak symbol, which means that it can be overwritten by the application or a shared library. Hence, LD_PRELOAD is not necessarily needed. Instead, I implemented the following function in a shared … Read more
You can only have one flexible array member in a struct, and it must always be the last member of the struct. In other words, in this case you’ve gone wrong before you call malloc, to the point that there’s really no way to call malloc correctly for this struct. To do what you seem … Read more
Yes, guaranteed by the C Standard if the new object can be allocated. (C99, 7.20.3.4p2) “The realloc function deallocates the old object pointed to by ptr and returns a pointer to a new object that has the size specified by size.”
No they’re not absolutely the same. While both let you store the same number and type of objects, keep in mind that: You can free() a malloced array, but you can’t free() a variable length array (although it goes out of scope and ceases to exist once the enclosing block is left). In technical jargon, … Read more
alloc() is not a standard C library function. Some older compilers and libraries contain an <alloc.h> library which provides some memory allocation functions, but this is not standard. The Microsoft Visual C++ runtime includes an Alloc() function which is somewhat similar to malloc(), but this is also not part of the C standard. malloc() allocates … Read more
As was indicated by others, you don’t need to use malloc just to do: const char *foo = “bar”; The reason for that is exactly that *foo is a pointer — when you initialize foo you’re not creating a copy of the string, just a pointer to where “bar” lives in the data section of … Read more