View Compilation Error

0_0_38454598_6130.cpp: In function 'int main()':
0_0_38454598_6130.cpp:11:20: error: 'memset' was not declared in this scope
   memset(c, 0, 1000);
                    ^
0_0_38454598_6130.cpp:15:18: error: 'strlen' was not declared in this scope
   la = strlen(ch1);
                  ^