View Compilation Error

0_0_19426731_21011.cpp: In function 'int main()':
0_0_19426731_21011.cpp:14:21: error: 'strlen' was not declared in this scope
         n = strlen(a);
                     ^
0_0_19426731_21011.cpp:16:29: error: 'memset' was not declared in this scope
         memset(c,0,sizeof(c));
                             ^