能否讲解一下有关文件的问题

#include <stdio.h> 

main() 

{ FILE *fp; int a[10]={1,2,3},i,n; 

fp=fopen("dl.dat","w"); 

for(i=0;i<3;i++) fprintf(fp,"%d",a[i]); 

fprintf(fp,"\n"); 

fclose(fp); 

fp=fopen("dl.dat","r"); 

fscanf(fp,"%d",&n); 

fclose(fp); 

printf("%d\n",n); 

} 

为什么结果是123不是1

for(i=0;i<3;i++) fprintf(fp,"%d",a[i]); ,存入时没加空格