View Compilation Error

0_0_22225486_14300.cpp: In function 'bool work(char*)':
0_0_22225486_14300.cpp:8:16: error: 'strlen' was not declared in this scope
  int l=strlen(s);
                ^
0_0_22225486_14300.cpp: In function 'bool jian(char*, char*)':
0_0_22225486_14300.cpp:34:17: error: 'strlen' was not declared in this scope
  int la=strlen(a);
                 ^
0_0_22225486_14300.cpp: In function 'int main(int, char**)':
0_0_22225486_14300.cpp:57:21: error: 'strcpy' was not declared in this scope
    strcpy(ans[cnt],s);
                     ^