View Compilation Error

0_0_21848030_3215.cpp: In function 'int main()':
0_0_21848030_3215.cpp:49:25: error: 'memset' was not declared in this scope
   memset(A, 0, sizeof(A));
                         ^
0_0_21848030_3215.cpp:52:19: error: 'strlen' was not declared in this scope
   int n = strlen(A);
                   ^