View Compilation Error

0_0_19215810_23569.cpp: In function 'void Inti(char*)':
0_0_19215810_23569.cpp:13:19: error: 'strlen' was not declared in this scope
  int len=strlen(ch);
                   ^
0_0_19215810_23569.cpp: In function 'int main()':
0_0_19215810_23569.cpp:33:22: error: 'strlen' was not declared in this scope
   int i,len=strlen(ch);
                      ^