c++ string和其他类型互转

来源：互联网发布：mp3剪切合并软件编辑：程序博客网时间：2024/05/29 08:20

c++中string和其他基本数据类型的转化总是需要自己实现，但是c++11给广大的c++程序员带来了福音，c++基础类型的相互转化变得非常简单。

其他类型 -> string

std::string to_string( int value );std::string to_string( long value );std::string to_string( long long value );std::string to_string( unsigned value );std::string to_string( unsigned long value );std::string to_string( unsigned long long value );std::string to_string( float value );std::string to_string( double value );std::string to_string( long double value );

例子：

#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); // Note: returns "0.000000"std::string f_str3 = std::to_string(f3); // Note: Does not return "1e+40".std::string f_str4 = std::to_string(f4); // Note: returns "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';}

string -> int

int stoi( const std::string& str, std::size_t* pos = 0, int base = 10 );int stoi( const std::wstring& str, std::size_t* pos = 0, int base = 10 );

string -> long

long stol( const std::string& str, std::size_t* pos = 0, int base = 10 );long stol( const std::wstring& str, std::size_t* pos = 0, int base = 10 );

string -> long long

long long stoll( const std::string& str, std::size_t* pos = 0, int base = 10 );long long stoll( const std::wstring& str, std::size_t* pos = 0, int base = 10 );

string -> unsigned long

unsigned long stoul( const std::string& str, std::size_t* pos = 0, int base = 10 );unsigned long stoul( const std::wstring& str, std::size_t* pos = 0, int base = 10 );

string -> unsigned long long

unsigned long long stoull( const std::string& str, std::size_t* pos = 0, int base = 10 );unsigned long long stoull( const std::wstring& str, std::size_t* pos = 0, int base = 10 );

string -> float

float stof( const std::string& str, std::size_t* pos = 0 );float stof( const std::wstring& str, std::size_t* pos = 0 );

string -> double

double stod( const std::string& str, std::size_t* pos = 0 );double stod( const std::wstring& str, std::size_t* pos = 0 );

string -> long double

long double stold( const std::string& str, std::size_t* pos = 0 );long double stold( const std::wstring& str, std::size_t* pos = 0 );

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