读/写在C二进制文件 [英] Read/Write to binary files in C

问题描述

有没有人有code的一个例子，可以写一个二进制文件。也code，可以读取一个二进制文件并输出到屏幕上。看着例子，我可以写一个文件就OK了但是当我尝试从没有正确输出文件中读取。

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

读取和写入二进制文件是pretty大致相同的任何其他文件，唯一的区别是如何打开它：

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

您说您能读它，但它无法正常输出......请记住，当你输出这个数据，你不读ASCII，所以它不是像打印字符串到屏幕上：

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

写入一个文件是pretty大致相同，与你使用的 的fwrite（） 而不是 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

---

由于我们正在谈论的Linux ..有一个简单的方法做一个全面的检查。在系统上安装 hexdump都（如果它不是已经在那里）和转储文件：

---

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
...

现在比较，为您的输出：

Now compare that to your output:

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

嗯，也许改变的printf 到％X 来使这一点更为清晰：

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！数据现在相匹配 ^* 。真棒，我们必须正确地读取二进制文件！

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

^{*注意字节只是交换的输出，但这些数据是正确的，你可以调整这样的事情}

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