在C ++中将二进制数据写入fstream [英] Writing binary data to fstream in c++
问题描述
我有一些要写入二进制文件的结构.它们由cstdint中的整数组成,例如 uint64_t
.有没有一种方法可以将这些文件写入二进制文件,而无需我手动将它们拆分为 char
数组并使用 fstream.write()
函数?
I have a few structures I want to write to a binary file. They consist of integers from cstdint, for example uint64_t
. Is there a way to write those to a binary file that doesn not involve me manually splitting them into arrays of char
and using the fstream.write()
functions?
我幼稚的想法是c ++会发现我有一个二进制模式的文件,而<<
会将整数写入该二进制文件.所以我尝试了这个:
My naive idea was that c++ would figure out that I have a file in binary mode and <<
would write the integers to that binary file. So I tried this:
#include <iostream>
#include <fstream>
#include <cstdint>
using namespace std;
int main() {
fstream file;
uint64_t myuint = 0xFFFF;
file.open("test.bin", ios::app | ios::binary);
file << myuint;
file.close();
return 0;
}
但是,这将字符串"65535"写入了文件.
However, this wrote the string "65535" to the file.
我可以以某种方式告诉fstream切换到二进制模式,例如如何使用<<更改显示格式.std :: hex
?
Can I somehow tell the fstream to switch to binary mode, like how I can change the display format with << std::hex
?
要使以上所有方法失败,我需要一个将任意cstdint类型转换为char数组的函数.
Failing all that above I'd need a function that turns arbitrary cstdint types into char arrays.
我并不真正担心字节序,因为我将使用相同的程序读取它们(在下一步中),因此它将被取消.
I'm not really concerned about endianness, as I'd use the same program to also read those (in a next step), so it would cancel out.
推荐答案
是的,这是 std :: fstream :: write
适用于:
Yes you can, this is what std::fstream::write
is for:
#include <iostream>
#include <fstream>
#include <cstdint>
int main() {
std::fstream file;
uint64_t myuint = 0xFFFF;
file.open("test.bin", std::ios::app | std::ios::binary);
file.write(reinterpret_cast<char*>(&myuint), sizeof(myuint)); // ideally, you should memcpy it to a char buffer.
}
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