输出的就不对了，就缺失字母，为什么啊？

Question

#include "stdafx.h"#include "stdio.h"int main(int argc, char* argv[]){FILE*fp,*fp2;fp=fopen("D:\\C\\file5\\file.txt","r");fp2=fopen("D:\\C\\file5\\file2.txt","w");if(fp==NULL)printf("cannot open file");if(fp2==NULL)printf("cannot open file2");char ch;while(!feof(fp)){ch=fgetc(fp);putchar(ch);fputc(ch,fp2);}fclose(fp);fclose(fp2);return 0;}如果while循环里改为：while(!feof(fp)){putchar(fgetc(fp));fputc(fgetc(fp,fp2);}输出内容file的内容：abcdefghijklmnopqrstuvwxyz

Answer 1

每次运行fgetc，都会重新去获得一次字符，你在putchar(fgetc(fp));中的fgetc所获得的字符，和fputc(fgetc(fp,fp2)所获得的字符是不同的两个字符。

Answer 2

while(!feof(fp))
{
putchar(fgetc(fp));
fweek(fp,ftell(fp)-1,0);\\这里加1句
fputc(fgetc(fp,fp2);
}