View Compilation Error

0_0_17076608_16828.cpp: In function 'void Polish(char*, int)':
0_0_17076608_16828.cpp:29:37: error: 'memset' was not declared in this scope
     memset(output,'\0',sizeof output);    
                                     ^
0_0_17076608_16828.cpp: In function 'int main()':
0_0_17076608_16828.cpp:135:35: error: 'strlen' was not declared in this scope
         Polish(input, strlen(input));
                                   ^