View Compilation Error

0_0_13858374_25272.cpp: In function 'int main()':
0_0_13858374_25272.cpp:20:25: error: 'strlen' was not declared in this scope
         int len=strlen(A);
                         ^
0_0_13858374_25272.cpp:31:28: error: 'memset' was not declared in this scope
         memset(a,0,sizeof a);
                            ^