C++ string与int的相互转换(使用C++11)
作者：李正浩大魔王
本文主要介绍了C++ string与int的相互转换(使用C++11)，文中通过示例代码介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们可以参考一下
一、int转string
#include <iostream>
#include <string>
int main()
{
double f = 23.43;
double f2 = 1e-9;
double f3 = 1e40;
double f4 = 1e-40;
double f5 = 123456789;
std::string f_str = std::to_string(f);
std::string f_str2 = std::to_string(f2); // 注意：返回 "0.000000"
std::string f_str3 = std::to_string(f3); // 注意：不返回 "1e+40".
std::string f_str4 = std::to_string(f4); // 注意：返回 "0.000000"
std::string f_str5 = std::to_string(f5);
std::cout << "std::cout: " << f << '\n'
<< "to_string: " << f_str << "\n\n"
<< "std::cout: " << f2 << '\n'
<< "to_string: " << f_str2 << "\n\n"
<< "std::cout: " << f3 << '\n'
<< "to_string: " << f_str3 << "\n\n"
<< "std::cout: " << f4 << '\n'
<< "to_string: " << f_str4 << "\n\n"
<< "std::cout: " << f5 << '\n'
<< "to_string: " << f_str5 << '\n';
}输出
std::cout: 23.43
to_string: 23.430000
std::cout: 1e-09
to_string: 0.000000
std::cout: 1e+40
to_string: 10000000000000000303786028427003666890752.000000
std::cout: 1e-40
to_string: 0.000000
std::cout: 1.23457e+08
to_string: 123456789.000000
二、string转int
#include <iostream>
#include <string>
int main()
{
std::string str1 = "45";
std::string str2 = "3.14159";
std::string str3 = "31337 with words";
std::string str4 = "words and 2";
int myint1 = std::stoi(str1);
int myint2 = std::stoi(str2);
int myint3 = std::stoi(str3);
// 错误： 'std::invalid_argument'
// int myint4 = std::stoi(str4);
std::cout << "std::stoi(\"" << str1 << "\") is " << myint1 << '\n';
std::cout << "std::stoi(\"" << str2 << "\") is " << myint2 << '\n';
std::cout << "std::stoi(\"" << str3 << "\") is " << myint3 << '\n';
//std::cout << "std::stoi(\"" << str4 << "\") is " << myint4 << '\n';
}结果：
std::stoi("45") is 45
std::stoi("3.14159") is 3
std::stoi("31337 with words") is 31337
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