#include"stdio.h"
#include"ctype.h"
#include"stdlib.h"
main(void)
    {
    int a=0,b;
    FILE *f1,*f2;
    char  f1name[20],f2name[20];
    char  str[30]="this is a test string";
/*在已存在的test.txt中输入数组str[]*/
    scanf("%s",&f1name);
    if((f1=fopen(f1name,"rb+"))==NULL)
         printf("failed to open the file1\n");
    else
         for(a;a<30;a++)
         fputc(str[a],f1);
         fclose(f1);       /*??*/
  /*将test1.txt中内容复制到test2.txt*/
     scanf("%s",&f2name);            
     if((f2=fopen(f2name,"w+"))==NULL)
        printf("failed to create a file\n");
     else
        f1=fopen(f1name,"r");      /*??*/
        while((b=getc(f1))!=EOF)
           fputc(b,f2);

     system("pause");
    }
弄不明白为什么少了？？的步骤 test2.txt就是空白文件

饿 自己学到重定向时写的  想到哪儿就写到哪儿 后面的好多都没学