C++ 错误：'itoa' 未在此范围内声明
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Error:‘itoa’ was not declared in this scope
提问by Green goblin
I am getting the following error:
prog.cpp: In member function ‘void Sequence::GetSequence()':
prog.cpp:45: error: ‘itoa' was not declared in this scope
我收到以下错误：
prog.cpp: 在成员函数 'void Sequence::GetSequence()':
prog.cpp:45: 错误: 'itoa' 未在此范围内声明
I have include cstdlib header file but its not working.
我已经包含 cstdlib 头文件，但它不起作用。
#include <iostream>
#include <string>
#include <vector>
#include <map>
#include <algorithm>
#include <functional>
using namespace std;
template<typename T>
struct predicate :
public binary_function<T, T, bool>
{
bool operator() (const T& l,const T &r) const
{
return l < r;
}
};
class Sequence
{
public:
Sequence(vector<string> &v)
{ /* trimmed */ }
void GetSequence(void)
{
string indices = "";
char buf[16];
for( map<int, string>::iterator
i = m.begin(); i != m.end(); ++i )
{
indices = indices
+ string(itoa((i->first), buf, 10));
}
SortedSequence("", indices);
}
// --- trimmed ---
回答by juanchopanza
There's no itoain the standard, but in C++11 you can use the std::to_stringfunctions.
itoa标准中没有，但在 C++11 中你可以使用std::to_string函数。
回答by pmr
In C++11 you can use std::to_string. If this is not available to you, you can use a std::stringstream:
在 C++11 中，您可以使用std::to_string. 如果这对您不可用，您可以使用std::stringstream：
std::stringstream ss; int x = 23;
ss << x;
std::string str = ss.str();
If this is too verbose, there is boost::lexical_cast. There are some complaints about the performance of lexical_castand std::stringstream, so watch out if this is important to you.
如果这太冗长，还有boost::lexical_cast。还有一些大概的性能的抱怨lexical_cast和std::stringstream，所以看出来，如果这对你很重要。
Another option is to use a Boost.Karma, a sublibrary of Spirit. It comes out ahead in most benchmarks.
另一种选择是使用Boost.Karma，它是 Spirit 的一个子库。它在大多数基准测试中领先。
Usually, itoais a bad idea. It is neither part of the C nor C++ standard. You can take some care to identify the platforms that support it and use it conditionally, but why should you, when there are better solutions.
通常，这itoa是一个坏主意。它既不是 C 也不是 C++ 标准的一部分。您可以谨慎地确定支持它的平台并有条件地使用它，但如果有更好的解决方案，为什么还要这样做。
回答by Vadzim
I've found that itoawas not available in MinGWGCC at least until 4.9.3 but isavailable in MinGW-w64GCC 5.3.0.
我发现itoa没有可用的MinGWGCC至少要等到4.9.3，但就是提供的MinGW-W64GCC 5.3.0。
It guess it's absense was related to broken vswprintfissue which also caused missing std::stoiand std::to_stringin MinGW.
它猜测它的缺席与损坏的 vswprintf问题有关，该问题也导致MinGW丢失。std::stoistd::to_string
