将浮点数转换为字符串的最快C ++方法 [英] Fastest C++ way to convert float to string

问题描述

我遇到了将浮点数转换为字符串的问题，其中 to_string 对我来说太慢了，因为我的数据可能涉及数百万个浮点数.

I have encountered problem of converting float to string where to_string is too slow for me as my data might involves few millions floats.

我已经对将这些数据快速写出.

但是，在解决了这个问题之后，我很快意识到，将float转换为string会产生很大的影响.

However, after solving that problem, I soon realized that the conversion of float to string is leaving a big impact.

那么，除了使用其他非标准库之外，还有其他想法或解决方案吗?

So, is there any ideas or solution for this other than using other non standard library?

推荐答案

想到的一种优化是不直接使用to_string，它每次调用时都会创建一个新字符串.您可能最终也会复制该字符串，效率不高.

An optimization that comes in mind is to not directly use to_string, which creates a new string every time you call it. You probably end up copying that string too, which is not so efficient.

您可以做的是分配一个足够大的char缓冲区，以存储所需的所有字符串表示形式，然后使用printf

What you could do is to allocate a char buffer big enough to store all the string representations that you need, then use printf

http://www.cplusplus.com/reference/cstdio/printf/

一直重复使用相同的缓冲区.如果将浮点数的精度限制为固定的小数位数，则可以计算浮点数在数组中所代表的偏移量.

reusing the same buffer all the time. If you limit the precision of your floats to a fixed amount of decimals, you can compute the offset to which your float is represented in the array.

例如，如果我们只有一个值数组:

for example if we only had an array of values:

index = 1;
float f = value[index];
//corrresponding 6 chars float
const char* s = char_array[index*1];
//the representation will start at position 6, and it will be null terminated so you can use it as a string

为澄清起见，您的char_array如下所示:

for clarification your char_array will look like:

1.2000\02.4324\0...

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