关于C语言fscanf的问题，好奇怪

Question

main()
{ FILE *fp;int i,k,n;
fp=fopen("data1.dat","w+");
for (i=1;i<=6;i++)
{fprintf(fp,"%d ",i);
if(i%3==0) fprintf(fp,"\n");
}
rewind(fp);

fscanf(fp,"%d%d",&k,&n);printf("%d，%d\n",k,n);
fclose(fp);

} /*为何不是输出123，456*/

main()
{ FILE *fp;int k,n,a[6]={1,2,3,4,5,6};
fp=fopen("d2.dat","w");
fprintf(fp,"%d%d%d\n",a[0],a[1],a[2]);
fprintf(fp,"%d%d%d\n",a[3],a[4],a[5]);

fclose(fp);
fp=fopen("d2.dat","r");;
fscanf(fp,"%d%d",&k,&n);
printf("%d,%d\n",k,n);
fclose(fp);

} /*为何又是输出123，456*/

两个程序好像没啥区别啊？怎么第二个数字就是连续读入k，n；第一个又不是？？？

Answer 1

#include "stdio.h"
main()
{ FILE *fp;int i,k,n;
fp=fopen("data1.dat","w+");
for (i=1;i<=6;i++)
{fprintf(fp,"%d ",i); ///这里%d后有空格，输出到文件中的数据是1 2 3 （第一行），fscanf读取时是以空格为分界的，所以只能读进来1，2
if(i%3==0) fprintf(fp,"\n");
}
rewind(fp);

fscanf(fp,"%d%d",&k,&n);printf("%d，%d\n",k,n);
fclose(fp);

}

main()
{ FILE *fp;int k,n,a[6]={1,2,3,4,5,6};
fp=fopen("d2.dat","w");
fprintf(fp,"%d%d%d\n",a[0],a[1],a[2]); ///这个输出到文件的格式为123 456
fprintf(fp,"%d%d%d\n",a[3],a[4],a[5]);

fclose(fp);
fp=fopen("d2.dat","r");;
fscanf(fp,"%d%d",&k,&n);
printf("%d,%d\n",k,n);
fclose(fp);

}

Answer 2

不认真，马虎~~