#include <cstring>
  void* memset( void* buffer, int ch, size_t count );

The function memset() copies ch into the first count characters of buffer, and returns buffer. memset() is useful for intializing a section of memory to some value. For example, this command:

   const int ARRAY_LENGTH;
   char the_array[ARRAY_LENGTH];
   ...
   // zero out the contents of the_array
   memset( the_array, '\0', ARRAY_LENGTH );

...is a very efficient way to set all values of the_array to zero.

The table below compares two different methods for initializing an array of characters: a for-loop versus memset(). As the size of the data being initialized increases, memset() clearly gets the job done much more quickly:

Input size	Initialized with a for-loop	Initialized with memset()
1000	0.016	0.017
10000	0.055	0.013
100000	0.443	0.029
1000000	4.337	0.291