将数据从一个文件复制到另一个文件的错误。

时间：2021-06-20 20:30:59

I want to copy the data from one file to other. But only one byte is copying.

我想把数据从一个文件复制到另一个文件。但只有一个字节在复制。

#include<stdio.h>

void main() {
   FILE *fp1, *fp2;
   char a;

   fp1 = fopen("test.jpg", "r");
   if (fp1 == NULL) {
      puts("cannot open this file");
      exit(1);
   }

   fp2 = fopen("test1.jpg", "w+");
   if (fp2 == NULL) {
      puts("Not able to open this file");
      fclose(fp1);
      exit(1);
   }

   do {
      a = fgetc(fp1);
      fputc(a, fp2);
   } while (a != EOF);

   fcloseall();
}

test.jpg consists of data ff d8 32 86 ..... But it is copying only ff and coming out of the while loop. Is i am doing any thing wrong

test.jpg包含数据ff d832 86……但它只是复制ff，从while循环中跳出来。我做错什么了吗?

1 个解决方案

#1

Declare a as int, not char.

声明a为int，而不是char。

int a;

Otherwise, that first 0xFF gets expanded into -1 (EOF).

否则，第一个0xFF将扩展为-1 (EOF)。

You should also open/close the files with b (for "binary"):

您还应该打开/关闭带有b的文件(用于“二进制”):

fp1 = fopen("test.jpg", "rb");

// ...

fp2 = fopen("test1.jpg", "w+b");

And, as Drew noted, check EOF before writing the character:

而且，正如Drew所指出的，在写这个角色之前要检查EOF:

while ((a = fgetc(fp1)) != EOF) {
  fputc(a, fp2);
}

#1