View Compilation Error

0_0_14903027_2098.cpp: In function 'mat operator*(mat&, mat&)':
0_0_14903027_2098.cpp:17:34: error: 'memset' was not declared in this scope
     memset( c.a , 0 , sizeof(c.a));
                                  ^
0_0_14903027_2098.cpp: In function 'mat operator^(mat&, int)':
0_0_14903027_2098.cpp:33:32: error: 'memset' was not declared in this scope
     memset( c.a, 0, sizeof(c.a));
                                ^