View Compilation Error

0_0_23209755_11618.cpp: In function 'int main()':
0_0_23209755_11618.cpp:8:16: error: 'strcpy' was not declared in this scope
      strcpy(c,a);
                ^
0_0_23209755_11618.cpp:9:16: error: 'strcat' was not declared in this scope
      strcat(c,a);
                ^
0_0_23209755_11618.cpp:10:19: error: 'strstr' was not declared in this scope
      if(strstr(c,b)!=NULL)
                   ^