View Compilation Error

0_0_20818488_18003.cpp: In function 'matrix operator*(const matrix&, const matrix&)':
0_0_20818488_18003.cpp:57:46: error: 'memset' was not declared in this scope
         memset(res.base , 0 ,sizeof(res.base));
                                              ^
0_0_20818488_18003.cpp: In function 'matrix pow(matrix, int)':
0_0_20818488_18003.cpp:68:45: error: 'memset' was not declared in this scope
         memset(res.base , 0 ,sizeof res.base);
                                             ^