单项选择题
有以下程序 #include<stdio.h>
main() { FILE*fp;int a[10]={1,2,3},i,n;
fp=fopen("d1.dat","w"); for(i=0;i<3;i++)
fprintf(fp,"%d",a[i]); fprintf(fp,"\n");
fclose(fp); fp=fopen("d1.dat","r");
fscanf(fp,"%d",&n); fclose(fp);
printf("%d\n",n); } 程序的运行结果是______。
A.12300
B.123
C.1
D.321