#include <set>
    size_type size() const;

The size() function returns the number of elements in the current set.

For example, the following code uses size() to determine the number of elements in a set:

     // Create a set of characters
     set<char> charSet;
     const char* s = "Hello There";
     for( int i=0; i < strlen(s); i++ ) {
       charSet.insert( s[i] );
     // Display the size of the set
     cout << charSet.size();
     // output is "8" (the characters in the set are " HTehlor")

Related Topics: empty