求助求助！有个程序，在运行到一半时出问题了．麻烦帮我看看．

[xtfusljj]

　　程序题目：在两个文件中输入两个集合的元素，再在另一个文件中输出它们的子集．我这个程序空集的时候是好的，一旦输入元素就不错误了．#include<stdio.h>
void main()
{
char ch;
FILE *fpa, *fpb, *fpc;
int n, k, count;
int i = 0, j = 0;
int a[1000];

printf("在磁盘中新建两个TXT文件，分别取名为a.txt,b.txt\n");
printf("分别在两个文件中输入两个集合的元素，输入完毕后以输入s表示开始执行求交集.\n");
printf( "若要在文件中输入空集则输入一个空格");

if((ch = getchar()) == 's')
{
fpa = fopen( "a.txt", "r");
fpb = fopen( "b.txt", "r");
if(((ch = fgetc(fpa)) == ' ')||((ch = fgetc(fpb)) == ' '))
{
fpc = fopen( "c.txt", "w");
printf("它们的交集已经在另外一个新建文件里了.");
fclose(fpb);
fclose(fpa);
}
if(((ch = fgetc(fpa)) != ' ')||((ch = fgetc(fpb)) != ' ')){
fclose(fpb);
fclose(fpa);
fpa = fopen( "a.txt", "r");
while( !feof(fpa))
{
fscanf(fpa, "%d", &n);
while( !feof(fpb))
{
fpb = fopen("b.txt", "r");
fscanf(fpb, "%d", &k);
if( n == k)
{
a[i] = n;
i ++ ;
}
count = i;
}
fclose(fpb);
}
fclose(fpa);
for( i = 0; i <= count; i ++ )
{
for( j = i + 1; j <= count; j ++ )
{
if(a[i] == a[j])
{
for(; j <= count; j ++)
{
a[j] = a[j+1];
count -- ;
}
}
}
}
fpc = fopen( "c.txt", "w");
for( i = 0; i <= count; i ++ )
{
fprintf(fpc, "%d\n", a[i]);
}
}
}
}

[我想我是人]

if(((ch = fgetc(fpa)) == ' ') ¦ ¦((ch = fgetc(fpb)) == ' '))
{
fpc = fopen( "c.txt", "w");
printf("它们的交集已经在另外一个新建文件里了.");
fclose(fpb);
fclose(fpa);
}

LZ..如果ch = fgetc(fpa)) == ' '成立而ch = fgetc(fpb)) == ' '不成立,那么该if块还是会执行的,之后会关闭fpa和fpb,那么后面的语句
if(((ch = fgetc(fpa)) != ' ') ¦ ¦((ch = fgetc(fpb)) != ' ')){
fclose(fpb);
fclose(fpa);
fpa = fopen( "a.txt", "r");
就会出错,因为fpa和fpb被关闭,即文件指针被关闭,无法读取数据,主要是C语言中的逻辑或和逻辑与的短路判定问题.