View Compilation Error

0_0_37778094_31694.cpp: In function 'node mul(node, node)':
0_0_37778094_31694.cpp:13:31: error: 'memset' was not declared in this scope
     memset(c.a, 0, sizeof(c.a));
                               ^
0_0_37778094_31694.cpp: In function 'void qsm_fac()':
0_0_37778094_31694.cpp:27:35: error: 'memset' was not declared in this scope
     memset(res.a, 0, sizeof(res.a));
                                   ^