严弘哲:C语言题请教

/*Demonstrates unary operatoot prefix and postfix modes*/

#include <stdio.h>

int a, b;

int main(void)
{
/*set a and b both equal to 1 */

a = b = 1;

/* Print them,decrementing each time.*/
/* Use prefix mode for b,prefix mode for a */

Printf("\nPost Pre");
Printf("\n%d %d", a++, ++b);
Printf("\n%d %d", a++, ++b);
Printf("\n%d %d", a++, ++b);
Printf("\n%d %d", a++, ++b);
Printf("\n%d %d", a++, ++b);

return 0;
}

这个程序有错吗?为什么我保存了后在没有看到程序,而是弹出了一个对话框显示内容如下:
C:\DOCUME~1\mly\LOCALS~1\Temp\ccwZcaaa.o(.text+0x40):456.c: undefined reference to `Printf'
C:\DOCUME~1\mly\LOCALS~1\Temp\ccwZcaaa.o(.text+0x68):456.c: undefined reference to `Printf'
C:\DOCUME~1\mly\LOCALS~1\Temp\ccwZcaaa.o(.text+0x90):456.c: undefined reference to `Printf'
C:\DOCUME~1\mly\LOCALS~1\Temp\ccwZcaaa.o(.text+0xb8):456.c: undefined reference to `Printf'
C:\DOCUME~1\mly\LOCALS~1\Temp\ccwZcaaa.o(.text+0xe0):456.c: undefined reference to `Printf'
C:\DOCUME~1\mly\LOCALS~1\Temp\ccwZcaaa.o(.text+0x108):456.c: more undefined references to `Printf' follow
_________________________________________________________________

这个程序输出是: Post Per
1 2
2 3
3 4
4 5
5 6
对吗?