用C读写二进制文件? [英] Read and write to binary files in C?

问题描述

谁有可以写入二进制文件的代码示例.还有可以读取二进制文件并输出到屏幕的代码.查看示例我可以写入文件，但是当我尝试从文件中读取时，它没有正确输出.

Does anyone have an example of code that can write to a binary file. And also code that can read a binary file and output to screen. Looking at examples I can write to a file ok But when I try to read from a file it is not outputting correctly.

推荐答案

二进制文件的读写与其他文件几乎相同，唯一的区别在于打开方式:

Reading and writing binary files is pretty much the same as any other file, the only difference is how you open it:

unsigned char buffer[10];
FILE *ptr;

ptr = fopen("test.bin","rb");  // r for read, b for binary

fread(buffer,sizeof(buffer),1,ptr); // read 10 bytes to our buffer

你说你可以阅读它，但它没有正确输出......请记住，当你输出"这个数据时，你不是在阅读 ASCII，所以它不像在屏幕上打印一个字符串:

You said you can read it, but it's not outputting correctly... keep in mind that when you "output" this data, you're not reading ASCII, so it's not like printing a string to the screen:

for(int i = 0; i<10; i++)
    printf("%u ", buffer[i]); // prints a series of bytes

写入文件几乎相同，除了您使用的是 fwrite() 而不是 fread():

Writing to a file is pretty much the same, with the exception that you're using fwrite() instead of fread():

FILE *write_ptr;

write_ptr = fopen("test.bin","wb");  // w for write, b for binary

fwrite(buffer,sizeof(buffer),1,write_ptr); // write 10 bytes from our buffer

<小时>

既然我们谈论的是 Linux.. 有一种简单的方法可以进行健全性检查.在你的系统上安装 hexdump(如果它还没有的话)并转储你的文件:

---

Since we're talking Linux.. there's an easy way to do a sanity check. Install hexdump on your system (if it's not already on there) and dump your file:

mike@mike-VirtualBox:~/C$ hexdump test.bin
0000000 457f 464c 0102 0001 0000 0000 0000 0000
0000010 0001 003e 0001 0000 0000 0000 0000 0000
...

现在将其与您的输出进行比较:

Now compare that to your output:

mike@mike-VirtualBox:~/C$ ./a.out 
127 69 76 70 2 1 1 0 0 0

hmm，也许将 printf 更改为 %x 以使其更清晰:

hmm, maybe change the printf to a %x to make this a little clearer:

mike@mike-VirtualBox:~/C$ ./a.out 
7F 45 4C 46 2 1 1 0 0 0

嘿，看！数据现在匹配^*.太棒了，我们必须正确读取二进制文件！

Hey, look! The data matches up now^*. Awesome, we must be reading the binary file correctly!

^{*注意字节只是在输出上交换，但数据是正确的，你可以针对这种事情进行调整}

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