View Compilation Error

0_0_20185227_13023.cpp: In function 'int main()':
0_0_20185227_13023.cpp:12:32: error: 'memset' was not declared in this scope
          memset(a, 0, sizeof(a));
                                ^
0_0_20185227_13023.cpp:16:26: error: 'strlen' was not declared in this scope
          a[0] = strlen(sa);
                          ^