View Compilation Error

0_0_26465809_19166.cpp: In function 'void getnx(char*)':
0_0_26465809_19166.cpp:10:18: error: 'strlen' was not declared in this scope
  int len=strlen(s);
                  ^
0_0_26465809_19166.cpp: In function 'int getindex(int, char*)':
0_0_26465809_19166.cpp:23:22: error: 'strlen' was not declared in this scope
  int len = strlen(tmp);
                      ^
0_0_26465809_19166.cpp: In function 'int main()':
0_0_26465809_19166.cpp:44:16: error: 'strlen' was not declared in this scope
   tn = strlen(t);
                ^