新手求助

#include<stdio.h>
main()
{
int a,b,c,d,e;
a = 40-22;
b = 90*60;
c = 100/20;
d = 10-2;
e = 9+1;
printf("结果是%d\n",a);
printf("结果是%d\n",b);
printf("结果是%d\n",c);
printf("结果是%d\n",d);
printf("结果是%d\n",e);
}
d:\program files\microsoft visual studio\myprojects\fdfd\fd.cpp(9) : error C2065: 'printf' : undeclared identifier
d:\program files\microsoft visual studio\myprojects\fdfd\fd.cpp(14) : warning C4508: 'main' : function should return a value; 'void' return type assumed
执行 cl.exe 时出错.