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#include<stdio.h>
int main()
{
FILE *fp;
int i,k=0,n=0;
fp=fopen("d1.dat","w");
for(i=1;i<4;i++)
fprintf(fp,"%d",i);
fclose(fp);
fp=fopen("d1.dat","r");
fscanf(fp,"%d%d",&k,&n);
printf("%d %d\n",k,n);
fclose(fp);
return 0;
}
#include<stdio.h>
int main()
{
union myun{
struct{int x,y,z;}u;
int k;
}a;
a.u.y=5;a.u.x=4;a.u.z=6;
a.k=0;
printf("%d%d%d\n",a.u.x,a.u.y,a.u.z);
return 0;
}
#include<stdio.h>
int main()
{
FILE *fp;
int i,k=0,n=0;
fp=fopen("d1.dat","w");
for(i=1;i<4;i++)
fprintf(fp,"%d",i);//写进去时候每行只有一个数字,最终结果是第一至第三行依次为123
fclose(fp);
fp=fopen("d1.dat","r");
fscanf(fp,"%d%d",&k,&n);//你想读两个数字,可是只有一个数字每行
printf("%d %d\n",k,n);
fclose(fp);
return 0;
}
如果改成这样:
#include<stdio.h>
int main()
{
FILE *fp;
int i,k=0,n=0;
fp=fopen("d1.dat","w");
for(i=1;i<4;i++)
fprintf(fp,"%d%d",i,i+1);//这样才是每行有两个数,n不会空
fclose(fp);
fp=fopen("d1.dat","r");
fscanf(fp,"%d%d",&k,&n);
printf("%d %d\n",k,n);
fclose(fp);
return 0;
}
#include<stdio.h>
int main()
{
union myun{
struct{int x,y,z;}u;
long k;
long long m;
}a;
a.u.y=5;
a.u.x=4;
a.u.z=6;
a.k=1;
a.m=0x00000000200000003;
printf("int = %d long = %ld long long = %ld \n",
sizeof(int), sizeof(long), sizeof(long long));
printf("%d %d %d %d %ld \n",
a.u.x,
a.u.y,
a.u.z,
sizeof(a),
a.m);
return 0;
}