View Compilation Error

0_0_29895008_7986.cpp: In function 'int main()':
0_0_29895008_7986.cpp:17:31: error: 'memset' was not declared in this scope
         memset(a,'0',sizeof(a));
                               ^
0_0_29895008_7986.cpp:24:23: error: 'strlen' was not declared in this scope
         temp1=strlen(a);
                       ^