View Compilation Error

0_0_21501707_29174.cpp: In constructor 'Trie_Node::Trie_Node()':
0_0_21501707_29174.cpp:13:60: error: 'memset' was not declared in this scope
     Trie_Node():fail(0),count(0){memset(next,0,sizeof(next));}
                                                            ^
0_0_21501707_29174.cpp: In function 'void insert(Trie_Position, char*)':
0_0_21501707_29174.cpp:44:27: error: 'strlen' was not declared in this scope
     for(int i=0,l=strlen(p),key;key=p[i]-'a',l-i>0;i++)
                           ^
0_0_21501707_29174.cpp:44:33: error: 'key' was not declared in this scope
     for(int i=0,l=strlen(p),key;key=p[i]-'a',l-i>0;i++)
                                 ^
0_0_21501707_29174.cpp: In function 'int StrMatching(Trie_Position, char*)':
0_0_21501707_29174.cpp:86:27: error: 'strlen' was not declared in this scope
     for(int i=0,l=strlen(t),key;key=t[i]-'a',l-i>0;i++)
                           ^
0_0_21501707_29174.cpp:86:33: error: 'key' was not declared in this scope
     for(int i=0,l=strlen(t),key;key=t[i]-'a',l-i>0;i++)
                                 ^