/in/foo.c: In function 'main':
/in/foo.c:6:3: error: 'cout' undeclared (first use in this function)
   cout << "输入大小：" << endl;
   ^
/in/foo.c:6:3: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:6:32: error: 'endl' undeclared (first use in this function)
   cout << "输入大小：" << endl;
                                ^
/in/foo.c:7:3: error: 'cin' undeclared (first use in this function)
   cin >> a[m] >> a[m + 1];
   ^