C语言 如何将整数写入文件（fprintf 和 fwrite 的区别）
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how to write an integer to a file (the difference between fprintf and fwrite)
提问by Shai Balassiano
I've been trying to write an integer to a file (open mode is w). fprintf wrote it correctly but fwrite wrote gibberish:
我一直在尝试将一个整数写入文件（打开模式是 w）。fprintf 写得正确，但 fwrite 写的是胡言乱语：
int length;
char * word = "word";
counter = strlen(word);
fwrite(&length, sizeof(int), 1, file);
fwrite(word, sizeof(char), length, file);
and the result in the file is:
文件中的结果是：
word
单词
but if I use fprintf instead, like this:
但是如果我改用 fprintf，就像这样：
int length;
char * word = "word";
counter = strlen(firstWord);
fprintf(file, "%d", counter);
fwrite(word, sizeof(char), length, file);
I get this result in the file:
我在文件中得到这个结果：
4word
四字
can anyone tell what I did wrong? thanks!
谁能告诉我我做错了什么？谢谢！
update: I would eventually like to change the writing to binary (I will open the file in wb mode), will there be a difference in my implementation?
更新：我最终想将写入更改为二进制（我将以 wb 模式打开文件），我的实现会有所不同吗？
回答by vanza
fprintfwrites a string. fwritewrites bytes. So in your first case, you're writing the bytes that represent an integer to the file; if its value is "4", the four bytes will be in the non-printable ASCII range, so you won't see them in a text editor. But if you look at the size of the file, it will probably be 8, not 4 bytes.
fprintf写一个字符串。fwrite写入字节。因此，在第一种情况下，您将表示整数的字节写入文件；如果其值为“4”，则四个字节将在不可打印的 ASCII 范围内，因此您将不会在文本编辑器中看到它们。但是如果您查看文件的大小，它可能是 8 个字节，而不是 4 个字节。
回答by David R Tribble
Using printf()converts the integer into a series of characters, in this case "4". Using fwrite()causes the actual bytes comprising the integer value to be written, in this case, the 4 bytes for the characters 'w', 'o', 'r',and 'd'.
使用printf()将整数转换为一系列字符，在本例中为"4"。使用fwrite()会导致写入包含整数值的实际字节，在这种情况下，是字符'w', 'o', 'r',和的 4 个字节'd'。
