View Compilation Error

0_0_22066493_1411.cpp: In function 'void buildsa(char*, int, int)':
0_0_22066493_1411.cpp:12:26: error: 'memset' was not declared in this scope
     memset(c , 0 , m << 2);
                          ^
0_0_22066493_1411.cpp: In function 'int main()':
0_0_22066493_1411.cpp:58:21: error: 'strlen' was not declared in this scope
         n = strlen(s);
                     ^