String To Lower/Upper in C++

Question

What is the best way people have found to do String to Lower case / Upper case in C++?

The issue is complicated by the fact that C++ isn\'t an English only programmi

Answer 1

You should also review this question. Basically the problem is that the standard C/C++ libraries weren't built to handle Unicode data, so you will have to look to other libraries.

This may change as the C++ standard is updated. I know the next compiler from Borland (CodeGear) will have Unicode support, and I would guess Microsoft's C++ compiler will have, or already has string libraries that support Unicode.

Answer 2

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

This will work, but this will use the standard "C" locale. You can use facets if you need to get a tolower for another locale. The above code using facets would be:

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

As Darren told you, the easiest method is to use std::transform.

But beware that in some language, like German for instance, there isn't always a one to one mapping between lower and uppercase. The "esset" lowercase character (look like the Greek character beta) is transformed to "SS" in uppercase.

Answer 4

The VCL has a SysUtils.hpp which has LowerCase(unicodeStringVar) and UpperCase(unicodeStringVar) which might work for you. I use this in C++ Builder 2009.

Answer 5

#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/

Also, CodeProject article for common string methods: http://www.codeproject.com/KB/stl/STL_string_util.aspx

Answer 6

My solution with my extras

Based on Kyle_the_hacker's -----> answer.

Ubuntu

In terminal List all locales
locale -a

Install all locales
sudo apt-get install -y locales locales-all

Compile main.cpp
$ g++ main.cpp

Run compiled program
$ ./a.out

Results

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

In cmd run VCVARS developer tools
"C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvars64.bat"

Compile 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

Run main.exe
>main.exe

Results

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

The code - main.cpp

This code was only tested on Windows x64 and Ubuntu Linux x64.

/*
 * 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;
}