Is it better to use malloc or calloc to allocate memory?

In general using malloc is faster, since calloc initializes the allocated memory to contain all zeroes. If this is what you want, however, then calloc can be used. The results can vary among different operating systems and environments, though. Memory allocation in an OS that uses floating blocks in heaps, such as Microsoft Windows and MacOS, should use the OS-native memory allocators instead. "Use malloc() almost always and calloc() almost never." The reason is that the initialization to zero that calloc() performs is usually not very helpful: - The initialization to "all-bits-zero" is not necessarily the same as initialization to "all-data-zero." C says very little about the representation of values in memory, nothing at all for floating-point or pointer values. On many machines all-bits-zero representations will in fact correspond to f.p. zeroes or null pointers, but this is not guaranteed by the language and there have been machines where the correspondence did not hold. If you get in the habit of using calloc() to initialize f.p. and pointer items, you may be heading for trouble. - Usually, one allocates a chunk of dynamic memory in order to store something in it -- and when you store something in it, you'll overwrite whatever was there before. Thus, the initialization performed by calloc() is usually not needed anyhow. There are occasional exceptions where all- bits-zero initialization is helpful, but they are unusual.