转到磁盘文件

#include 
int main()
{
 FILE *fp;
 char ch;
 fp=fopen("demo.txt","w");
 if(fp==NULL)
 {
   printf("failure to open demo.txt!\n");
 exit(0);

 }
 ch=getchar();
 while (ch!='\n')
 {
     fputc(ch,fp);
     ch=getchar();
 }
    fclose(fp);
    return 0;
}