View Compilation Error

0_0_24062838_13108.cpp: In function 'void Polish(char*, int)':
0_0_24062838_13108.cpp:28:41: error: 'memset' was not declared in this scope
         memset(output,'\0',sizeof output);  //输出串  
                                         ^
0_0_24062838_13108.cpp: In function 'int main()':
0_0_24062838_13108.cpp:139:39: error: 'strlen' was not declared in this scope
             Polish(input, strlen(input));  
                                       ^