转到磁盘文件

#include <stdio.h>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;}