求大佬解答

#include <stdio.h>
#include <math.h>
void man()
{
double x,s;
printf("input number:\n");
scanf("%if,&x");
s=sin(x);
printf("sine of %if is %if\n");
}

报错：

--------------------Configuration: b - Win32 Debug--------------------
Linking...
LIBCD.lib(crt0.obj) : error LNK2001: unresolved external symbol _main
Debug/b.exe : fatal error LNK1120: 1 unresolved externals
执行 link.exe 时出错.

b.exe - 1 error(s), 0 warning(s)