知识点6 C++数据类型转换 string

发布时间：2020-12-16 09:15:10 所属栏目：百科来源：网络整理

导读：一、int转string 1.c++11标准增加了全局函数std::to_string: string to_string (int val); string to_string (long val); string to_string (long long val); string to_string (unsigned val); string to_string (unsigned long val); string to_string (un

一、int转string

1.c++11标准增加了全局函数std::to_string:

string to_string (int val);

string to_string (long val);

string to_string (long long val);

string to_string (unsigned val);

string to_string (unsigned 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);

Example:

// to_string example
#include <iostream>   // std::cout
#include <string>     // std::string,std::to_string
 
int main ()
{
  std::string pi = "pi is " + std::to_string(3.1415926);
  std::string perfect = std::to_string(1+2+4+7+14) + " is a perfect number";
  std::cout << pi << ‘n‘;
  std::cout << perfect << ‘n‘;
  return 0;
}

　　Output:

pi is 3.141593
28 is a perfect number

二、string转int

1.可以使用std::stoi/stol/stoll等等函数
Example:

// stoi example
#include <iostream>   // std::cout
#include <string>     // std::string,std::stoi
 
int main ()
{
  std::string str_dec = "2001,A Space Odyssey";
  std::string str_hex = "40c3";
  std::string str_bin = "-10010110001";
  std::string str_auto = "0x7f";
 
  std::string::size_type sz;   // alias of size_t
 
  int i_dec = std::stoi (str_dec,&sz);
  int i_hex = std::stoi (str_hex,nullptr,16);
  int i_bin = std::stoi (str_bin,2);
  int i_auto = std::stoi (str_auto,0);
 
  std::cout << str_dec << ": " << i_dec << " and [" << str_dec.substr(sz) << "]n";
  std::cout << str_hex << ": " << i_hex << ‘n‘;
  std::cout << str_bin << ": " << i_bin << ‘n‘;
  std::cout << str_auto << ": " << i_auto << ‘n‘;
 
  return 0;
}

　　Output:

2001,A Space Odyssey: 2001 and [,A Space Odyssey]
40c3:  16579
-10010110001: -1201
0x7f: 127

（编辑：李大同）

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