Ubuntu

Question

人们发现在C ++中使用String to Lower case / Upper case的最佳方法是什么？

C ++不是一种英语编程语言，这个问题很复杂。有一个很好的多语言方法吗？

Answer 1

#include <algorithm>
std::string data = "Abc";
std::transform(data.begin(), data.end(), data.begin(), ::toupper);

http://notfaq.wordpress.com/2007/08/04/cc-convert-string-to-upperlower-case/

此外，有关常见字符串方法的CodeProject文章：http://www.codeproject.com/KB/stl/STL_string_util.aspx

Answer 2

> std::string data = “Abc”; 
> std::transform(data.begin(), data.end(), data.begin(), ::toupper);

这将有效，但这将使用标准的“C”语言环境。如果您需要为另一个区域设置获得tolower，则可以使用facet。上面使用facet的代码是：

locale loc("");
const ctype<char>& ct = use_facet<ctype<char> >(loc);
transform(str.begin(), str.end(), std::bind1st(std::mem_fun(&ctype<char>::tolower), &ct));

Answer 3

对于希望使用Nic Strong答案的复制粘贴者，请注意“use_factet”中的拼写错误以及std :: transform缺少的第三个参数：

locale loc("");
const ctype<char>& ct = use_factet<ctype<char> >(loc);
transform(str.begin(), str.end(), std::bind1st(std::mem_fun(&ctype<char>::tolower), &ct));

应该是

locale loc("");
const ctype<char>& ct = use_facet<ctype<char> >(loc);
transform(str.begin(), str.end(), str.begin(), std::bind1st(std::mem_fun(&ctype<char>::tolower), &ct));

Answer 4

您还应该查看this question。基本上问题是标准的C / C ++库不是为处理Unicode数据而构建的，因此您必须查看其他库。

这可能会随着C ++标准的更新而改变。我知道Borland的下一个编译器（CodeGear）将支持Unicode，我猜想微软的C ++编译器会有，或者已经有了支持Unicode的字符串库。

Answer 5

Darren告诉你，最简单的方法是使用std :: transform。

但请注意，在某些语言中，例如德语，并不总是在小写和大写之间进行一对一的映射。 “esset”小写字符（看起来像希腊字符beta）以大写字母转换为“SS”。

Answer 6

如果你有Boost，那么它有最简单的方法。看看to_upper()/to_lower() in Boost string algorithms。

Answer 7

我找到了一种转换unicode（和多语言）字符的方法，但是你需要知道/找到（不知何故）字符的语言环境：

#include <locale.h>

_locale_t locale = _create_locale(LC_CTYPE, "Greek");
AfxMessageBox((CString)""+(TCHAR)_totupper_l(_T('α'), locale));
_free_locale(locale);

我还没有办法做到这一点......我知道如何，让我知道。

将语言环境设置为NULL不起作用...

Answer 8

VCL有一个SysUtils.hpp，LowerCase(unicodeStringVar)和UpperCase(unicodeStringVar)可能适合您。我在C ++ Builder 2009中使用它。

Answer 9

Steve说的是正确的，但我想如果你的代码必须支持多种语言，你可以使用一个工厂方法封装一组方法，这些方法根据该语言执行相关的toUpper或toLower。

Answer 10

我的附加服务解决方案

基于Kyle_the_hacker's -----> answer。

Ubuntu

在终端中列出所有语言环境
locale -a

安装所有语言环境
sudo apt-get install -y locales locales-all

编译main.cpp
$ g++ main.cpp

运行编译的程序
$ ./a.out

结果

Zoë Saldaña played in La maldición del padre Cardona. ëèñ αω óóChloë
Zoë Saldaña played in La maldición del padre Cardona. ëèñ αω óóChloë
ZOË SALDAÑA PLAYED IN LA MALDICIÓN DEL PADRE CARDONA. ËÈÑ ΑΩ ÓÓCHLOË
ZOË SALDAÑA PLAYED IN LA MALDICIÓN DEL PADRE CARDONA. ËÈÑ ΑΩ ÓÓCHLOË
zoë saldaña played in la maldición del padre cardona. ëèñ αω óóchloë
zoë saldaña played in la maldición del padre cardona. ëèñ αω óóchloë

Ubuntu VM

Windows

在cmd中运行VCVARS开发人员工具
"C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvars64.bat"

编译main.cpp
> cl /EHa main.cpp /D "_DEBUG" /D "_CONSOLE" /D "_UNICODE" /D "UNICODE" /std:c++17 /DYNAMICBASE "kernel32.lib" "user32.lib" "gdi32.lib" "winspool.lib" "comdlg32.lib" "advapi32.lib" "shell32.lib" "ole32.lib" "oleaut32.lib" "uuid.lib" "odbc32.lib" "odbccp32.lib" /MTd

Compilador de optimización de C/C++ de Microsoft (R) versión 19.27.29111 para x64
(C) Microsoft Corporation. Todos los derechos reservados.

main.cpp
Microsoft (R) Incremental Linker Version 14.27.29111.0
Copyright (C) Microsoft Corporation.  All rights reserved.

/out:main.exe
main.obj
kernel32.lib
user32.lib
gdi32.lib
winspool.lib
comdlg32.lib
advapi32.lib
shell32.lib
ole32.lib
oleaut32.lib
uuid.lib
odbc32.lib
odbccp32.lib

运行main.exe
>main.exe

结果

Zoë Saldaña played in La maldición del padre Cardona. ëèñ αω óóChloë
Zoë Saldaña played in La maldición del padre Cardona. ëèñ αω óóChloë
ZOË SALDAÑA PLAYED IN LA MALDICIÓN DEL PADRE CARDONA. ËÈÑ ΑΩ ÓÓCHLOË
ZOË SALDAÑA PLAYED IN LA MALDICIÓN DEL PADRE CARDONA. ËÈÑ ΑΩ ÓÓCHLOË
zoë saldaña played in la maldición del padre cardona. ëèñ αω óóchloë
zoë saldaña played in la maldición del padre cardona. ëèñ αω óóchloë

代码-main.cpp

此代码仅在Windows x64和Ubuntu Linux x64上进行过测试。

/*
 * Filename: c:\Users\x\Cpp\main.cpp
 * Path: c:\Users\x\Cpp
 * Filename: /home/x/Cpp/main.cpp
 * Path: /home/x/Cpp
 * Created Date: Saturday, October 17th 2020, 10:43:31 pm
 * Author: Joma
 *
 * No Copyright 2020
 */

#include <iostream>
#include <locale>
#include <string>
#include <algorithm>
#include <set>
#include <cstdlib>
#include <clocale>

#if defined(_WIN32)
#define WINDOWSLIB 1
#define DLLCALL STDCALL
#define DLLIMPORT _declspec(dllimport)
#define DLLEXPORT _declspec(dllexport)
#define DLLPRIVATE

#define NOMINMAX
#include <Windows.h>
#include <objbase.h>
#include <filesystem>
#include <intrin.h>
#include <conio.h>

#elif defined(__ANDROID__) || defined(ANDROID) //Android
#define ANDROIDLIB 1
#define DLLCALL CDECL
#define DLLIMPORT
#define DLLEXPORT __attribute__((visibility("default")))
#define DLLPRIVATE __attribute__((visibility("hidden")))

#elif defined(__APPLE__) //iOS, Mac OS
#define MACOSLIB 1
#define DLLCALL CDECL
#define DLLIMPORT
#define DLLEXPORT __attribute__((visibility("default")))
#define DLLPRIVATE __attribute__((visibility("hidden")))

#elif defined(__LINUX__) || defined(__gnu_linux__) || defined(__linux__) || defined(__linux) || defined(linux) //_Ubuntu - Fedora - Centos - RedHat
#define LINUXLIB 1
#include <cpuid.h>
#include <experimental/filesystem>
#include <unistd.h>
#include <termios.h>
#define DLLCALL CDECL
#define DLLIMPORT
#define DLLEXPORT __attribute__((visibility("default")))
#define DLLPRIVATE __attribute__((visibility("hidden")))
#define CoTaskMemAlloc(p) malloc(p)
#define CoTaskMemFree(p) free(p)

#elif defined(__EMSCRIPTEN__)
#define EMSCRIPTENLIB 1
#include <unistd.h>
#include <termios.h>
#define DLLCALL
#define DLLIMPORT
#define DLLEXPORT __attribute__((visibility("default")))
#define DLLPRIVATE __attribute__((visibility("hidden")))

#endif

typedef std::string String;
typedef std::wstring WString;
#define LINE_FEED_CHAR (static_cast<char>(10))

enum class ConsoleTextStyle
{
    DEFAULT = 0,
    BOLD = 1,
    FAINT = 2,
    ITALIC = 3,
    UNDERLINE = 4,
    SLOW_BLINK = 5,
    RAPID_BLINK = 6,
    REVERSE = 7,
};

enum class ConsoleForeground
{
    DEFAULT = 39,
    BLACK = 30,
    DARK_RED = 31,
    DARK_GREEN = 32,
    DARK_YELLOW = 33,
    DARK_BLUE = 34,
    DARK_MAGENTA = 35,
    DARK_CYAN = 36,
    GRAY = 37,
    DARK_GRAY = 90,
    RED = 91,
    GREEN = 92,
    YELLOW = 93,
    BLUE = 94,
    MAGENTA = 95,
    CYAN = 96,
    WHITE = 97
};

enum class ConsoleBackground
{
    DEFAULT = 49,
    BLACK = 40,
    DARK_RED = 41,
    DARK_GREEN = 42,
    DARK_YELLOW = 43,
    DARK_BLUE = 44,
    DARK_MAGENTA = 45,
    DARK_CYAN = 46,
    GRAY = 47,
    DARK_GRAY = 100,
    RED = 101,
    GREEN = 102,
    YELLOW = 103,
    BLUE = 104,
    MAGENTA = 105,
    CYAN = 106,
    WHITE = 107
};

class Console
{
public:
    static void Clear();
    static void WriteLine(const String &s, ConsoleForeground foreground = ConsoleForeground::DEFAULT, ConsoleBackground background = ConsoleBackground::DEFAULT, std::set<ConsoleTextStyle> styles = {});
    static void Write(const String &s, ConsoleForeground foreground = ConsoleForeground::DEFAULT, ConsoleBackground background = ConsoleBackground::DEFAULT, std::set<ConsoleTextStyle> styles = {});
    static void WriteLine(const WString &s, ConsoleForeground foreground = ConsoleForeground::DEFAULT, ConsoleBackground background = ConsoleBackground::DEFAULT, std::set<ConsoleTextStyle> styles = {});
    static void Write(const WString &s, ConsoleForeground foreground = ConsoleForeground::DEFAULT, ConsoleBackground background = ConsoleBackground::DEFAULT, std::set<ConsoleTextStyle> styles = {});
    static void WriteLine();
    static void Pause();
    static int PauseAny(bool printWhenPressed = false);

private:
    static void EnableVirtualTermimalProcessing();
    static void SetVirtualTerminalFormat(ConsoleForeground foreground, ConsoleBackground background, std::set<ConsoleTextStyle> styles);
    static void ResetTerminalFormat();
};

class Strings
{
public:
    static String WideStringToString(const WString &wstr);
    static WString StringToWideString(const String &str);
    static WString ToUpper(const WString &data);
    static String ToUpper(const String &data);
    static WString ToLower(const WString &data);
    static String ToLower(const String &data);
};

String Strings::WideStringToString(const WString &wstr)
{
    if (wstr.empty())
    {
        return String();
    }
    size_t pos;
    size_t begin = 0;
    String ret;
    size_t size;
#ifdef WINDOWSLIB
    pos = wstr.find(static_cast<wchar_t>(0), begin);
    while (pos != WString::npos && begin < wstr.length())
    {
        WString segment = WString(&wstr[begin], pos - begin);
        wcstombs_s(&size, nullptr, 0, &segment[0], _TRUNCATE);
        String converted = String(size, 0);
        wcstombs_s(&size, &converted[0], size, &segment[0], _TRUNCATE);
        ret.append(converted);
        begin = pos + 1;
        pos = wstr.find(static_cast<wchar_t>(0), begin);
    }
    if (begin <= wstr.length())
    {
        WString segment = WString(&wstr[begin], wstr.length() - begin);
        wcstombs_s(&size, nullptr, 0, &segment[0], _TRUNCATE);
        String converted = String(size, 0);
        wcstombs_s(&size, &converted[0], size, &segment[0], _TRUNCATE);
        converted.resize(size - 1);
        ret.append(converted);
    }
#elif defined LINUXLIB
    pos = wstr.find(static_cast<wchar_t>(0), begin);
    while (pos != WString::npos && begin < wstr.length())
    {
        WString segment = WString(&wstr[begin], pos - begin);
        size = wcstombs(nullptr, segment.c_str(), 0);
        String converted = String(size, 0);
        wcstombs(&converted[0], segment.c_str(), converted.size());
        ret.append(converted);
        ret.append({0});
        begin = pos + 1;
        pos = wstr.find(static_cast<wchar_t>(0), begin);
    }
    if (begin <= wstr.length())
    {
        WString segment = WString(&wstr[begin], wstr.length() - begin);
        size = wcstombs(nullptr, segment.c_str(), 0);
        String converted = String(size, 0);
        wcstombs(&converted[0], segment.c_str(), converted.size());
        ret.append(converted);
    }
#elif defined MACOSLIB
#endif

    return ret;
}

WString Strings::StringToWideString(const String &str)
{
    if (str.empty())
    {
        return WString();
    }

    size_t pos;
    size_t begin = 0;
    WString ret;
    size_t size;

#ifdef WINDOWSLIB
    pos = str.find(static_cast<char>(0), begin);
    while (pos != String::npos)
    {
        String segment = String(&str[begin], pos - begin);
        WString converted = WString(segment.size() + 1, 0);

        mbstowcs_s(&size, &converted[0], converted.size(), &segment[0], _TRUNCATE);
        converted.resize(size - 1);
        ret.append(converted);
        ret.append({0});
        begin = pos + 1;
        pos = str.find(static_cast<char>(0), begin);
    }
    if (begin < str.length())
    {
        String segment = String(&str[begin], str.length() - begin);
        WString converted = WString(segment.size() + 1, 0);
        mbstowcs_s(&size, &converted[0], converted.size(), &segment[0], _TRUNCATE);
        converted.resize(size - 1);
        ret.append(converted);
    }
#elif defined LINUXLIB
    pos = str.find(static_cast<char>(0), begin);
    while (pos != String::npos)
    {
        String segment = String(&str[begin], pos - begin);
        WString converted = WString(segment.size(), 0);
        size = mbstowcs(&converted[0], &segment[0], converted.size());
        converted.resize(size);
        ret.append(converted);
        ret.append({0});
        begin = pos + 1;
        pos = str.find(static_cast<char>(0), begin);
    }
    if (begin < str.length())
    {
        String segment = String(&str[begin], str.length() - begin);
        WString converted = WString(segment.size(), 0);
        size = mbstowcs(&converted[0], &segment[0], converted.size());
        converted.resize(size);
        ret.append(converted);
    }
#elif defined MACOSLIB
#endif

    return ret;
}

WString Strings::ToUpper(const WString &data)
{
    WString result = data;
    auto &f = std::use_facet<std::ctype<wchar_t>>(std::locale());

    f.toupper(&result[0], &result[0] + result.size());
    return result;
}

String Strings::ToUpper(const String &data)
{
    return WideStringToString(ToUpper(StringToWideString(data)));
}

WString Strings::ToLower(const WString &data)
{
    WString result = data;
    auto &f = std::use_facet<std::ctype<wchar_t>>(std::locale());
    f.tolower(&result[0], &result[0] + result.size());
    return result;
}

String Strings::ToLower(const String &data)
{
    return WideStringToString(ToLower(StringToWideString(data)));
}

void Console::Clear()
{

#ifdef WINDOWSLIB
    std::system(u8"cls");
#elif defined LINUXLIB
    std::system(u8"clear");
#elif defined EMSCRIPTENLIB
    emscripten::val::global()["console"].call<void>(u8"clear");
#elif defined MACOSLIB
#endif
}

void Console::Pause()
{
    char c;
    do
    {
        c = getchar();
    } while (c != LINE_FEED_CHAR);
}

int Console::PauseAny(bool printWhenPressed)
{
    int ch;
#ifdef WINDOWSLIB
    ch = _getch();
#elif defined LINUXLIB
    struct termios oldt, newt;
    tcgetattr(STDIN_FILENO, &oldt);
    newt = oldt;
    newt.c_lflag &= ~(ICANON | ECHO);
    tcsetattr(STDIN_FILENO, TCSANOW, &newt);
    ch = getchar();
    tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
#elif defined MACOSLIB
#endif
    return ch;
}

void Console::EnableVirtualTermimalProcessing()
{
#if defined WINDOWSLIB
    HANDLE hOut = GetStdHandle(STD_OUTPUT_HANDLE);
    DWORD dwMode = 0;
    GetConsoleMode(hOut, &dwMode);
    if (!(dwMode & ENABLE_VIRTUAL_TERMINAL_PROCESSING))
    {
        dwMode |= ENABLE_VIRTUAL_TERMINAL_PROCESSING;
        SetConsoleMode(hOut, dwMode);
    }
#endif
}

void Console::ResetTerminalFormat()
{
    std::cout << u8"\033[0m";
}

void Console::SetVirtualTerminalFormat(ConsoleForeground foreground, ConsoleBackground background, std::set<ConsoleTextStyle> styles)
{
    String format = u8"\033[";
    format.append(std::to_string(static_cast<int>(foreground)));
    format.append(u8";");
    format.append(std::to_string(static_cast<int>(background)));
    if (styles.size() > 0)
    {
        for (auto it = styles.begin(); it != styles.end(); ++it)
        {
            format.append(u8";");
            format.append(std::to_string(static_cast<int>(*it)));
        }
    }
    format.append(u8"m");
    std::cout << format;
}

void Console::Write(const String &s, ConsoleForeground foreground, ConsoleBackground background, std::set<ConsoleTextStyle> styles)
{
    EnableVirtualTermimalProcessing();
    SetVirtualTerminalFormat(foreground, background, styles);
    String str = s;
#ifdef WINDOWSLIB
    WString unicode = Strings::StringToWideString(str);
    WriteConsole(GetStdHandle(STD_OUTPUT_HANDLE), unicode.c_str(), static_cast<DWORD>(unicode.length()), nullptr, nullptr);
#elif defined LINUXLIB
    std::cout << str;
#elif defined MACOSLIB
#endif
    ResetTerminalFormat();
}

void Console::WriteLine(const String &s, ConsoleForeground foreground, ConsoleBackground background, std::set<ConsoleTextStyle> styles)
{
    Write(s, foreground, background, styles);
    std::cout << std::endl;
}

void Console::Write(const WString &s, ConsoleForeground foreground, ConsoleBackground background, std::set<ConsoleTextStyle> styles)
{
    EnableVirtualTermimalProcessing();
    SetVirtualTerminalFormat(foreground, background, styles);
    WString str = s;

#ifdef WINDOWSLIB
    WriteConsole(GetStdHandle(STD_OUTPUT_HANDLE), str.c_str(), static_cast<DWORD>(str.length()), nullptr, nullptr);
#elif defined LINUXLIB
    std::cout << Strings::WideStringToString(str); //NEED TO BE FIXED. ADD locale parameter
#elif defined MACOSLIB
#endif
    ResetTerminalFormat();
}

void Console::WriteLine(const WString &s, ConsoleForeground foreground, ConsoleBackground background, std::set<ConsoleTextStyle> styles)
{
    Write(s, foreground, background, styles);
    std::cout << std::endl;
}

int main()
{
    std::locale::global(std::locale(u8"en_US.UTF-8"));
    String dataStr = u8"Zoë Saldaña played in La maldición del padre Cardona. ëèñ αω óóChloë";
    WString dataWStr = L"Zoë Saldaña played in La maldición del padre Cardona. ëèñ αω óóChloë";
    std::string locale = u8"";
    //std::string locale = u8"de_DE.UTF-8";
    //std::string locale = u8"en_US.UTF-8";
    Console::WriteLine(dataStr);
    Console::WriteLine(dataWStr);
    dataStr = Strings::ToUpper(dataStr);
    dataWStr = Strings::ToUpper(dataWStr);
    Console::WriteLine(dataStr);
    Console::WriteLine(dataWStr);
    dataStr = Strings::ToLower(dataStr);
    dataWStr = Strings::ToLower(dataWStr);
    Console::WriteLine(dataStr);
    Console::WriteLine(dataWStr);
    Console::PauseAny();
    return 0;
}

字符串在C ++中降低/降低

10 个答案:

Ubuntu

Windows

代码-main.cpp