View Compilation Error

0_0_30698830_11842.cpp: In constructor 'matrix::matrix()':
0_0_30698830_11842.cpp:15:27: error: 'memset' was not declared in this scope
   memset(num,0,sizeof(num));
                           ^
0_0_30698830_11842.cpp: In member function 'void matrix::atom()':
0_0_30698830_11842.cpp:18:27: error: 'memset' was not declared in this scope
   memset(num,0,sizeof(num));
                           ^