经典c程序 输入输出

#include "stdio.h"
main()
{ FILE *fp;
int i,j,n,ni;
char c[160],t,ch;
if((fp=fopen("A","r"))==NULL)
{printf("file A cannot be opened/n");
exit(0);}
printf("/n A contents are :/n");
for(i=0;(ch=fgetc(fp))!=EOF;i++)
{c[i]=ch;
putchar(c[i]);
}
fclose(fp);
ni=i;
if((fp=fopen("B","r"))==NULL)
{printf("file B cannot be opened/n");
exit(0);}
printf("/n B contents are :/n");
for(i=0;(ch=fgetc(fp))!=EOF;i++)
{c[i]=ch;
putchar(c[i]);
}
fclose(fp);
n=i;
for(i=0;i<n;i++)
for(j=i+1;j<n;j++)
if(c[i]>c[j])
{t=c[i];c[i]=c[j];c[j]=t;}
printf("/n C file is:/n");
fp=fopen("C","w");
for(i=0;i<n;i++)
{ putc(c[i],fp);
putchar(c[i]);
}
fclose(fp);
}