View Compilation Error

0_0_24469538_8224.cpp: In function 'int add(char*, int)':
0_0_24469538_8224.cpp:39:42: error: 'memset' was not declared in this scope
    memset(tree[now], 0, sizeof(tree[now]));
                                          ^
0_0_24469538_8224.cpp: In function 'int main()':
0_0_24469538_8224.cpp:87:35: error: 'memset' was not declared in this scope
   memset(tree[0],0,sizeof(tree[0]));
                                   ^
0_0_24469538_8224.cpp:97:22: error: 'strlen' was not declared in this scope
    int ssize=strlen(s);
                      ^