C++ 将 int 转换为 char 数组的最佳方法
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Optimal way to convert an int into a char array
提问by Kacper Fa?at
What is the best method (performance) to put an intinto a chararray?
This is my current code:
将 anint放入char数组的最佳方法（性能）是什么？这是我当前的代码：
data[0] = length & 0xff;
data[1] = (length >> 8) & 0xff;
data[2] = (length >> 16) & 0xff;
data[3] = (length >> 24) & 0xff;
datais a chararray (shared ptr) and lengthis the int.
data是一个char数组（共享 ptr）并且length是int.
回答by Rahul Tripathi
Are you looking for memcpy
你在找 memcpy
char x[20];
int a;
memcpy(&a,x,sizeof(int));
Your solution is also good as it is endian safe.
您的解决方案也很好，因为它是endian safe。
On a side note:-
附注：-
Although there is no such guarantee that sizeof(int)==4for any particular implementation.
尽管sizeof(int)==4对于任何特定的实现都没有这样的保证。
回答by Yochai Timmer
Just use reinterpret_cast. Use the data array as if it were an int pointer.
只需使用reinterpret_cast. 像使用 int 指针一样使用数据数组。
char data[sizeof(int)];
*reinterpret_cast<int*>(data) = length;
BTW memcpyis much slower than this, because it copies byte by byte using a loop.
In the case of an integer, this will just be a straightforward assignment.
顺便说一句，memcpy比这慢得多，因为它使用循环逐字节复制。
在整数的情况下，这只是一个简单的赋值。
