View Compilation Error

0_0_26301487_24100.cpp: In member function 'void t::init()':
0_0_26301487_24100.cpp:26:37: error: 'memset' was not declared in this scope
   memset(tree[0], 0, sizeof(tree[0]));
                                     ^
0_0_26301487_24100.cpp: In member function 'void t::add(char, int)':
0_0_26301487_24100.cpp:48:50: error: 'memset' was not declared in this scope
    memset(tree[newnode], 0, sizeof(tree[newnode]));
                                                  ^