std :: lexical_cast - 有这样的事吗？ [英] std::lexical_cast - is there such a thing?

问题描述

C ++标准库定义了这个函数，还是我必须求助于Boost？

我在网络上搜索过，除了Boost，

<对于内置类型，p> C ++ 11 < string> 有 std :: to_string p>

[n3290：21.5 / 7]：

  string to_string（int val）; 
 string to_string（unsigned val）; 
 string to_string（long val）; 
 string to_string（unsigned long val）; 
 string to_string（long long val）; 
 string to_string（unsigned long long val）; 
 string to_string（float val）; 
 string to_string（double val）; 
 string to_string（long double val）; 
  

返回：每个函数返回 string 对象保存其参数值的
字符表示，
通过调用 sprintf（buf，fmt，val）生成格式
％d，％u，％ld，％lu，％lld ，％llu，
％f，％f 或％Lf，其中 buf




还有以下情况：

[n3290：21.5 / 1，21.5 / 4]：

  int stoi（con​​st string& str，size_t * idx = 0，int base = 10）; 
 long stol（const string& str，size_t * idx = 0，int base = 10）; 
 unsigned long stoul（const string& str，size_t * idx = 0，int base = 10）; 
 long long stoll（const string& str，size_t * idx = 0，int base = 10）; 
 unsigned long long stoull（const string& str，size_t * idx = 0，int base = 10）; 
 float stof（const string& str，size_t * idx = 0）; 
 double stod（const string& str，size_t * idx = 0）; 
 long double stold（const string& str，size_t * idx = 0）; 
  

但是，没有什么可以使用的通用a href =http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1973.html>直到TR2 ，也许！），什么都没有C ++ 03。

Does the C++ Standard Library define this function, or do I have to resort to Boost?

I searched the web and couldn't find anything except Boost, but I thought I'd better ask here.

解决方案

Only partially.

C++11 <string> has std::to_string for the built-in types:

[n3290: 21.5/7]:

string to_string(int val);
string to_string(unsigned val);
string to_string(long val);
string to_string(unsigned long val);
string to_string(long long val);
string to_string(unsigned long long val);
string to_string(float val);
string to_string(double val);
string to_string(long double val);

Returns: Each function returns a string object holding the character representation of the value of its argument that would be generated by calling sprintf(buf, fmt, val) with a format specifier of "%d", "%u", "%ld", "%lu", "%lld", "%llu", "%f", "%f", or "%Lf", respectively, where buf designates an internal character buffer of sufficient size.

There are also the following that go the other way around:

[n3290: 21.5/1, 21.5/4]:

int stoi(const string& str, size_t *idx = 0, int base = 10);
long stol(const string& str, size_t *idx = 0, int base = 10);
unsigned long stoul(const string& str, size_t *idx = 0, int base = 10);
long long stoll(const string& str, size_t *idx = 0, int base = 10);
unsigned long long stoull(const string& str, size_t *idx = 0, int base = 10);
float stof(const string& str, size_t *idx = 0);
double stod(const string& str, size_t *idx = 0);
long double stold(const string& str, size_t *idx = 0);

However, there's nothing generic that you can use (at least not until TR2, maybe!), and nothing at all in C++03.

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