求助!大一字符数组排序!
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define N 20
int main()
{
FILE *fp1,*fp2,*fp3;
char s1[N],s2[N],temp;
int i,j;
if((fp1=fopen("D:\\6.13\\A.txt","r"))==NULL)
{
printf("cannot open file\n");
exit(0);
}
if((fp2=fopen("D:\\6.13\\B.txt","r"))==NULL)
{
printf("cannot open file\n");
exit(0);
}
fgets(s1,N,fp1);
fgets(s2,N,fp2);
strcat(s1,s2);
fclose(fp1);
fclose(fp2);
for(i=0;i<N;i++)
{
if(s1[i]>='A'&&s1[i]<='Z') s1[i]+=32;
}
puts(s1);
for(i=0;i<2*N-1;i++)
{
for(j=0;j<2*N-1-i;j++)
{
if(s1[j]>s1[j+1])
{
temp=s1[j];
s1[j]=s1[j+1];
s1[j+1]=temp;
}
}
}
puts(s1);
if((fp3=fopen("D:\\6.13\\C.txt","w"))==NULL)
{
printf("cannot open file\n");
exit(0);
}
fputs(s1,fp3);
fputs("\n",fp3);
return 0;
}
为何最后S1是空的??