View Compilation Error

0_0_36071595_28937.cpp: In constructor 'matrix::matrix()':
0_0_36071595_28937.cpp:20:32: error: 'memset' was not declared in this scope
  matrix(){ memset(x,0,sizeof(x));}
                                ^
0_0_36071595_28937.cpp: In function 'int main()':
0_0_36071595_28937.cpp:36:2: error: 'cin' was not declared in this scope
  cin>>t;
  ^