在 C++ 中填充 stl 字符串
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【中文标题】在 C++ 中填充 stl 字符串【英文标题】：Padding stl strings in C++ 【发布时间】：2010-10-14 14:37:21 【问题描述】：我正在使用std::string 并且需要将它们填充到给定的宽度。在 C++ 中推荐的方法是什么？
示例输入：
123
填充到 10 个字符。
示例输出：
123
（123前面7个空格）
【问题讨论】：
【参考方案1】：std::setw (setwidth) 操纵器
std::cout << std::setw (10) << 77 << std::endl;
或
std::cout << std::setw (10) << "hi!" << std::endl;
输出填充的 77 和“hi！”。
如果您需要结果作为字符串，请使用 std::stringstream 的实例而不是 std::cout 对象。
ps：负责头文件<iomanip>
【讨论】：
很棒的答案。我们有没有机会以最小的工作示例的形式得到这个？谢谢 对于一个简单的std::to_string(n) 使用stringstream 似乎开销很大...【参考方案2】：
void padTo(std::string &str, const size_t num, const char paddingChar = ' ')
if(num > str.size())
str.insert(0, num - str.size(), paddingChar);
int main(int argc, char **argv)
std::string str = "abcd";
padTo(str, 10);
return 0;
【讨论】：
我喜欢这个解决方案，因为在各种 linux OS 风格的字符串流需要一个不可用的 GLIBC 依赖项。 insert(0, ...) 是个坏主意，因为它很慢，每次插入新字符时都需要复制字符串。 @arhuaco 为什么std::string::insert() 会复制一份？它在一个缓冲区上运行。这不是 Java/C#。如果您想要糟糕的性能，请选择任何带有流的解决方案...
@ebyrob 我误读了代码。这是相当不错。顺便说一句，在 LeftPad 崩溃之后，我把 some code 当作一个玩笑实现了，它非常相似（就地版本）。【参考方案3】：
你可以这样使用它：
std::string s = "123";
s.insert(s.begin(), paddedLength - s.size(), ' ');
【讨论】：
【参考方案4】：我能想到的最简单的方法是使用字符串流：
string foo = "foo";
stringstream ss;
ss << setw(10) << foo;
foo = ss.str();
foo 现在应该被填充了。
【讨论】：
【参考方案5】：你可以通过调用来创建一个包含N个空格的字符串
string(N, ' ');
所以你可以这样做：
string to_be_padded = ...;
if (to_be_padded.size() < 10)
string padded(10 - to_be_padded.size(), ' ');
padded += to_be_padded;
return padded;
else return to_be_padded;
【讨论】：
最佳答案，但格式很糟糕，难以阅读【参考方案6】：std::string pad_right(std::string const& str, size_t s)
if ( str.size() < s )
return str + std::string(s-str.size(), ' ');
else
return str;
std::string pad_left(std::string const& str, size_t s)
if ( str.size() < s )
return std::string(s-str.size(), ' ') + str;
else
return str;
【讨论】：
最佳答案 - 除了可怕的缺乏花括号。 :)【参考方案7】：有一个不错的简单方法:)
const int required_pad = 10;
std::string myString = "123";
size_t length = myString.length();
if (length < required_pad)
myString.insert(0, required_pad - length, ' ');
【讨论】：
【参考方案8】：怎么样：
string s = " "; // 10 spaces
string n = "123";
n.length() <= 10 ? s.replace(10 - n.length(), n.length(), s) : s = n;
【讨论】：
【参考方案9】：最少的工作代码：
#include <iostream>
#include <iomanip>
int main()
for(int i = 0; i < 300; i += 11)
std::cout << std::setfill ( ' ' ) << std::setw (2) << (i % 100) << std::endl;
return 0;
/*
Note:
- for std::setfill ( ' ' ):
- item in '' is what will be used for filling
- std::cout may be replaced with a std::stringstream if you need it
- modulus is used to cut the integer to an appropriate length, for strings use substring
- std::setw is used to define the length of the needed string
*/
【讨论】：
【参考方案10】：在https://repl.it/@JomaCorpFX/Padding#main.cpp上测试这段代码
我们有 2 种类型的 Padding
普通填充字符串的每个字符都是一个单独的元素
std::string str = u8"Hello"; //5 elements
std::string str2 = u8"Hello ?"; //10 elements // ? has 4 chars.
std::string str3 = u8"?"; //4 elements // ? has 4 chars.
长度为UTF8单位，一个UTF8单位可以是1-4个字符
std::string str = u8"Hello"; //5 UTF8 units.
std::string str2 = u8"Hello ?"; //7 UTF8 units // ? is an individual element.
std::string str3 = u8"?"; //1 UTF8 units
函数
class Strings
static size_t LengthUTF8(const String& data);
static String SubstringUTF8(const String& data, size_t startIndex, size_t length);
static String PadRight(const String& data, const size_t& totalWidth, const char& padding);
static String PadLeft(const String& data, const size_t& totalWidth, const char& padding);
static String PadRight(const String& data, const size_t& totalWidth, const String& padding);
static String PadLeft(const String& data, const size_t& totalWidth, const String& padding);
static String PadRightUTF8(const String& data, const size_t& totalWidth, const char& padding);
static String PadLeftUTF8(const String& data, const size_t& totalWidth, const char& padding);
static String PadRightUTF8(const String& data, const size_t& totalWidth, const String& padding);
static String PadLeftUTF8(const String& data, const size_t& totalWidth, const String& padding);
;
以 UTF8 结尾的函数以 UTF8 单位处理字符串以确定其长度。不以 UTF8 结尾的函数会以每个 char 为单位来确定长度。
如果填充是一个字符串，如果它是一个 UTF8 函数，它将以 UTF8 单位处理，否则作为字符处理。
totalWidth 参数是基于函数 normal 或 UTF8。
全码
#include <iostream>
#include <set>
#include <string>
#include <locale>
// WINDOWS
#if (_WIN32)
#include <Windows.h>
#include <conio.h>
#define WINDOWS_PLATFORM 1
#define DLLCALL STDCALL
#define DLLIMPORT _declspec(dllimport)
#define DLLEXPORT _declspec(dllexport)
#define DLLPRIVATE
#define NOMINMAX
//EMSCRIPTEN
#elif defined(__EMSCRIPTEN__)
#include <emscripten/emscripten.h>
#include <emscripten/bind.h>
#include <unistd.h>
#include <termios.h>
#define EMSCRIPTEN_PLATFORM 1
#define DLLCALL
#define DLLIMPORT
#define DLLEXPORT __attribute__((visibility("default")))
#define DLLPRIVATE __attribute__((visibility("hidden")))
// LINUX - Ubuntu, Fedora, , Centos, Debian, RedHat
#elif (__LINUX__ || __gnu_linux__ || __linux__ || __linux || linux)
#define LINUX_PLATFORM 1
#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)
//android
#elif (__ANDROID__ || ANDROID)
#define ANDROID_PLATFORM 1
#define DLLCALL
#define DLLIMPORT
#define DLLEXPORT __attribute__((visibility("default")))
#define DLLPRIVATE __attribute__((visibility("hidden")))
//MACOS
#elif defined(__APPLE__)
#include <unistd.h>
#include <termios.h>
#define DLLCALL
#define DLLIMPORT
#define DLLEXPORT __attribute__((visibility("default")))
#define DLLPRIVATE __attribute__((visibility("hidden")))
#include "TargetConditionals.h"
#if TARGET_OS_IPHONE && TARGET_IPHONE_SIMULATOR
#define IOS_SIMULATOR_PLATFORM 1
#elif TARGET_OS_IPHONE
#define IOS_PLATFORM 1
#elif TARGET_OS_MAC
#define MACOS_PLATFORM 1
#else
#endif
#endif
typedef std::string String;
typedef std::wstring WString;
#define EMPTY_STRING u8""s
#define EMPTY_WSTRING L""s
using namespace std::literals::string_literals;
class Strings
public:
static String WideStringToString(const WString& wstr)
if (wstr.empty())
return String();
size_t pos;
size_t begin = 0;
String ret;
#if WINDOWS_PLATFORM
int size;
pos = wstr.find(static_cast<wchar_t>(0), begin);
while (pos != WString::npos && begin < wstr.length())
WString segment = WString(&wstr[begin], pos - begin);
size = WideCharToMultiByte(CP_UTF8, WC_ERR_INVALID_CHARS, &segment[0], segment.size(), NULL, 0, NULL, NULL);
String converted = String(size, 0);
WideCharToMultiByte(CP_UTF8, WC_ERR_INVALID_CHARS, &segment[0], segment.size(), &converted[0], converted.size(), NULL, NULL);
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 = WideCharToMultiByte(CP_UTF8, WC_ERR_INVALID_CHARS, &segment[0], segment.size(), NULL, 0, NULL, NULL);
String converted = String(size, 0);
WideCharToMultiByte(CP_UTF8, WC_ERR_INVALID_CHARS, &segment[0], segment.size(), &converted[0], converted.size(), NULL, NULL);
ret.append(converted);
#elif LINUX_PLATFORM || MACOS_PLATFORM || EMSCRIPTEN_PLATFORM
size_t size;
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);
#else
static_assert(false, "Unknown Platform");
#endif
return ret;
static WString StringToWideString(const String& str)
if (str.empty())
return WString();
size_t pos;
size_t begin = 0;
WString ret;
#ifdef WINDOWS_PLATFORM
int size = 0;
pos = str.find(static_cast<char>(0), begin);
while (pos != std::string::npos)
std::string segment = std::string(&str[begin], pos - begin);
std::wstring converted = std::wstring(segment.size() + 1, 0);
size = MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, &segment[0], segment.size(), &converted[0], converted.length());
converted.resize(size);
ret.append(converted);
ret.append( 0 );
begin = pos + 1;
pos = str.find(static_cast<char>(0), begin);
if (begin < str.length())
std::string segment = std::string(&str[begin], str.length() - begin);
std::wstring converted = std::wstring(segment.size() + 1, 0);
size = MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, segment.c_str(), segment.size(), &converted[0], converted.length());
converted.resize(size);
ret.append(converted);
#elif LINUX_PLATFORM || MACOS_PLATFORM || EMSCRIPTEN_PLATFORM
size_t size;
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);
#else
static_assert(false, "Unknown Platform");
#endif
return ret;
static size_t LengthUTF8(const String& data)
size_t ret = 0;
for (char value : data)
if ((value & 0xc0) != 0x80)
++ret;
return ret;
static String SubstringUTF8(const String& data, size_t startIndex, size_t length)
size_t units = LengthUTF8(data);
if (startIndex >= units)
throw std::invalid_argument(u8"Invalid UTF8 character position.");
String result;
String::const_iterator it = data.begin();
String::const_iterator beginIterator = data.begin();
size_t endIndex = length == SIZE_MAX ? units : startIndex + length;
size_t utf8pos = 0;
while (it != data.end())
char value = *it;
if ((value & 0xc0) != 0x80) // Es inicio de caracter //utf8pos = 0 / beginIterator = 0 / endIndex = 1+12
if (utf8pos == startIndex)
beginIterator = it;
if (length >= units)
return String(beginIterator, data.end());
if (utf8pos == endIndex)
break;
utf8pos += 1;
it++;
return String(beginIterator, it);
static String GetCharUTF8(const String& data, size_t pos)
return SubstringUTF8(data, pos, 1);
static String PadRight(const String& data, const size_t& totalWidth, const char& padding)
if (data.length() >= totalWidth)
return data;
String ret = data;
ret.resize(totalWidth, padding);
return ret;
static String PadLeft(const String& data, const size_t& totalWidth, const char& padding)
if (data.length() >= totalWidth)
return data;
String ret = data;
ret.insert(0, totalWidth - ret.length(), padding);
return ret;
static String PadRight(const String& data, const size_t& totalWidth, const String& padding)
if (data.length() >= totalWidth)
return data;
size_t modulo = (totalWidth - data.length()) % padding.length();
size_t paddingUnits = (totalWidth - data.length()) / padding.length();
String ret = data;
for (size_t i = 0; i < paddingUnits; i++)
ret.append(padding);
ret.append(padding.substr(0, modulo));
return ret;
static String PadLeft(const String& data, const size_t& totalWidth, const String& padding)
if (data.length() >= totalWidth)
return data;
size_t modulo = (totalWidth - data.length()) % padding.length();
size_t paddingUnits = (totalWidth - data.length()) / padding.length();
String ret = data;
for (size_t i = 0; i < paddingUnits; i++)
ret.insert(0, padding);
ret.insert(0, padding.substr(0, modulo));
return ret;
static String PadRightUTF8(const String& data, const size_t& totalWidth, const char& padding)
size_t totalUtf8 = LengthUTF8(data);
if (totalUtf8 >= totalWidth)
return data;
String ret = data;
ret.resize(ret.length() + (totalWidth - totalUtf8), padding);
return ret;
static String PadLeftUTF8(const String& data, const size_t& totalWidth, const char& padding)
size_t totalUtf8 = LengthUTF8(data);
if (totalUtf8 >= totalWidth)
return data;
String ret = data;
ret.insert(0, totalWidth - totalUtf8, padding);
return ret;
static String PadRightUTF8(const String& data, const size_t& totalWidth, const String& padding)
size_t units = LengthUTF8(data);
size_t paddingUnits = LengthUTF8(padding);
if (units >= totalWidth)
return data;
size_t modulo = (totalWidth - units) % paddingUnits;
size_t n = (totalWidth - units) / paddingUnits;
String ret = data;
for (size_t i = 0; i < n; i++)
ret.append(padding);
ret.append(SubstringUTF8(padding, 0, modulo));
return ret;
static String PadLeftUTF8(const String& data, const size_t& totalWidth, const String& padding)
size_t units = LengthUTF8(data);
size_t paddingUnits = LengthUTF8(padding);
if (units >= totalWidth)
return data;
size_t modulo = (totalWidth - units) % paddingUnits;
size_t n = (totalWidth - units) / paddingUnits;
String ret = data;
for (size_t i = 0; i < n; i++)
ret.insert(0, padding);
ret.insert(0, SubstringUTF8(padding, 0, modulo));
return ret;
;
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 //For Printing Unicode strings.
private:
static void EnableVirtualTermimalProcessing()
#if defined WINDOWS_PLATFORM
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
static void ResetTerminalFormat()
std::cout << u8"\033[0m";
static void 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;
public:
static void Clear()
#ifdef WINDOWS_PLATFORM
std::system(u8"cls");
#elif LINUX_PLATFORM || defined MACOS_PLATFORM
std::system(u8"clear");
#elif EMSCRIPTEN_PLATFORM
emscripten::val::global()["console"].call<void>(u8"clear");
#else
static_assert(false, "Unknown Platform");
#endif
static void Write(const String& s, ConsoleForeground foreground = ConsoleForeground::DEFAULT, ConsoleBackground background = ConsoleBackground::DEFAULT, std::set<ConsoleTextStyle> styles = )
#ifndef EMSCRIPTEN_PLATFORM
EnableVirtualTermimalProcessing();
SetVirtualTerminalFormat(foreground, background, styles);
#endif
String str = s;
#ifdef WINDOWS_PLATFORM
WString unicode = Strings::StringToWideString(str);
WriteConsole(GetStdHandle(STD_OUTPUT_HANDLE), unicode.c_str(), static_cast<DWORD>(unicode.length()), nullptr, nullptr);
#elif defined LINUX_PLATFORM || defined MACOS_PLATFORM || EMSCRIPTEN_PLATFORM
std::cout << str;
#else
static_assert(false, "Unknown Platform");
#endif
#ifndef EMSCRIPTEN_PLATFORM
ResetTerminalFormat();
#endif
static void WriteLine(const String& s, ConsoleForeground foreground = ConsoleForeground::DEFAULT, ConsoleBackground background = ConsoleBackground::DEFAULT, std::set<ConsoleTextStyle> styles = )
Write(s, foreground, background, styles);
std::cout << std::endl;
static void Write(const WString& s, ConsoleForeground foreground = ConsoleForeground::DEFAULT, ConsoleBackground background = ConsoleBackground::DEFAULT, std::set<ConsoleTextStyle> styles = )
#ifndef EMSCRIPTEN_PLATFORM
EnableVirtualTermimalProcessing();
SetVirtualTerminalFormat(foreground, background, styles);
#endif
WString str = s;
#ifdef WINDOWS_PLATFORM
WriteConsole(GetStdHandle(STD_OUTPUT_HANDLE), str.c_str(), static_cast<DWORD>(str.length()), nullptr, nullptr);
#elif LINUX_PLATFORM || MACOS_PLATFORM || EMSCRIPTEN_PLATFORM
std::cout << Strings::WideStringToString(str);
#else
static_assert(false, "Unknown Platform");
#endif
#ifndef EMSCRIPTEN_PLATFORM
ResetTerminalFormat();
#endif
static void WriteLine(const WString& s, ConsoleForeground foreground = ConsoleForeground::DEFAULT, ConsoleBackground background = ConsoleBackground::DEFAULT, std::set<ConsoleTextStyle> styles = )
Write(s, foreground, background, styles);
std::cout << std::endl;
static void WriteLine()
std::cout << std::endl;
static void Pause()
char c;
do
c = getchar();
std::cout << "Press Key " << std::endl;
while (c != 64);
std::cout << "KeyPressed" << std::endl;
static int PauseAny(bool printWhenPressed = false, ConsoleForeground foreground = ConsoleForeground::DEFAULT, ConsoleBackground background = ConsoleBackground::DEFAULT, std::set<ConsoleTextStyle> styles = )
int ch;
#ifdef WINDOWS_PLATFORM
ch = _getch();
#elif LINUX_PLATFORM || MACOS_PLATFORM || EMSCRIPTEN_PLATFORM
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);
#else
static_assert(false, "Unknown Platform");
#endif
if (printWhenPressed)
Console::Write(String(1, ch), foreground, background, styles);
return ch;
;
int main()
//u8"?" 4 char units
char charPadding = u8'@';
std::string stringPadding = u8"<>"s;
std::string unicodeStringPadding = u8"?"s;
std::locale::global(std::locale(u8"en_US.UTF8"));
//No UTF8 examples
String str = u8"Hello ?"s;
Console::WriteLine(u8"Original: " + str + u8" █ StrLength: " + std::to_string(str.length()) + u8" █ UTF8Chars: " + std::to_string(Strings::LengthUTF8(str)) + u8" █ Padded:" + Strings::PadLeft(str, 10, charPadding) + u8" █ PadLeft with char padding");//"Hello ?" No changes. Length 10 == totalWith 10
Console::WriteLine(u8"Original: " + str + u8" █ StrLength: " + std::to_string(str.length()) + u8" █ UTF8Chars: " + std::to_string(Strings::LengthUTF8(str)) + u8" █ Padded:" + Strings::PadLeft(str, 15, charPadding) + u8" █ PadLeft with char padding");//"@@@@@Hello ?"
str = u8"Hello ?"s;
Console::WriteLine(u8"Original: " + str + u8" █ StrLength: " + std::to_string(str.length()) + u8" █ UTF8Chars: " + std::to_string(Strings::LengthUTF8(str)) + u8" █ Padded:" + Strings::PadRight(str, 10, charPadding) + u8" █ PadRight with char padding");//"Hello ?" No changes. Length 10 == totalWith 10
Console::WriteLine(u8"Original: " + str + u8" █ StrLength: " + std::to_string(str.length()) + u8" █ UTF8Chars: " + std::to_string(Strings::LengthUTF8(str)) + u8" █ Padded:" + Strings::PadRight(str, 15, charPadding) + u8" █ PadRight with char padding");//"Hello ?@@@@@"
str = u8"Hello ?"s;
Console::WriteLine(u8"Original: " + str + u8" █ StrLength: " + std::to_string(str.length()) + u8" █ UTF8Chars: " + std::to_string(Strings::LengthUTF8(str)) + u8" █ Padded:" + Strings::PadLeft(str, 10, stringPadding) + u8" █ PadLeft with string padding");//"Hello ?" No changes. Length 10 == totalWith 10
Console::WriteLine(u8"Original: " + str + u8" █ StrLength: " + std::to_string(str.length()) + u8" █ UTF8Chars: " + std::to_string(Strings::LengthUTF8(str)) + u8" █ Padded:" + Strings::PadLeft(str, 15, stringPadding) + u8" █ PadLeft with string padding");//"<<><>Hello ?"
str = u8"Hello ?"s;
Console::WriteLine(u8"Original: " + str + u8" █ StrLength: " + std::to_string(str.length()) + u8" █ UTF8Chars: " + std::to_string(Strings::LengthUTF8(str)) + u8" █ Padded:" + Strings::PadRight(str, 10, stringPadding) + u8" █ PadRight with string padding");//"Hello ?" No changes. Length 10 == totalWith 10
Console::WriteLine(u8"Original: " + str + u8" █ StrLength: " + std::to_string(str.length()) + u8" █ UTF8Chars: " + std::to_string(Strings::LengthUTF8(str)) + u8" █ Padded:" + Strings::PadRight(str, 15, stringPadding) + u8" █ PadRight with string padding");//"Hello ?<><><"
//UTF8 Examples
str = u8"Hello ?"s;
Console::WriteLine(u8"Original: " + str + u8" █ StrLength: " + std::to_string(str.length()) + u8" █ UTF8Chars: " + std::to_string(Strings::LengthUTF8(str)) + u8" █ Padded:" + Strings::PadLeftUTF8(str, 7, charPadding) + u8" █ PadLeftUTF8 with char padding");//"Hello ?" No changes. UTF8Length 7 == totalWith 7
Console::WriteLine(u8"Original: " + str + u8" █ StrLength: " + std::to_string(str.length()) + u8" █ UTF8Chars: " + std::to_string(Strings::LengthUTF8(str)) + u8" █ Padded:" + Strings::PadLeftUTF8(str, 15, charPadding) + u8" █ PadLeftUTF8 with char padding");//"@@@@@@@@Hello ?"
str = u8"Hello ?"s;
Console::WriteLine(u8"Original: " + str + u8" █ StrLength: " + std::to_string(str.length()) + u8" █ UTF8Chars: " + std::to_string(Strings::LengthUTF8(str)) + u8" █ Padded:" + Strings::PadRightUTF8(str, 7, charPadding) + u8" █ PadRightUTF8 with char padding");//"Hello ?" No changes. UTF8Length 7 == totalWith 7
Console::WriteLine(u8"Original: " + str + u8" █ StrLength: " + std::to_string(str.length()) + u8" █ UTF8Chars: " + std::to_string(Strings::LengthUTF8(str)) + u8" █ Padded:" + Strings::PadRightUTF8(str, 15, charPadding) + u8" █ PadRightUTF8 with char padding");//"Hello ?@@@@@@@@"
str = u8"Hello ?"s;
Console::WriteLine(u8"Original: " + str + u8" █ StrLength: " + std::to_string(str.length()) + u8" █ UTF8Chars: " + std::to_string(Strings::LengthUTF8(str)) + u8" █ Padded:" + Strings::PadLeftUTF8(str, 7, unicodeStringPadding) + u8" █ PadLeftUTF8 with string padding");//"Hello ?" No changes. UTF8Length 7 == totalWith 7
Console::WriteLine(u8"Original: " + str + u8" █ StrLength: " + std::to_string(str.length()) + u8" █ UTF8Chars: " + std::to_string(Strings::LengthUTF8(str)) + u8" █ Padded:" + Strings::PadLeftUTF8(str, 15, unicodeStringPadding) + u8" █ PadLeftUTF8 with string padding");//"????????Hello ?"
str = u8"Hello ?"s;
Console::WriteLine(u8"Original: " + str + u8" █ StrLength: " + std::to_string(str.length()) + u8" █ UTF8Chars: " + std::to_string(Strings::LengthUTF8(str)) + u8" █ Padded:" + Strings::PadRightUTF8(str, 7, unicodeStringPadding) + u8" █ PadRightUTF8 with string padding");//"Hello ?" No changes. UTF8Length 7 == totalWith 7
Console::WriteLine(u8"Original: " + str + u8" █ StrLength: " + std::to_string(str.length()) + u8" █ UTF8Chars: " + std::to_string(Strings::LengthUTF8(str)) + u8" █ Padded:" + Strings::PadRightUTF8(str, 15, unicodeStringPadding) + u8" █ PadRightUTF8 with string padding");//"Hello ?????????"
Console::WriteLine();
Console::WriteLine(u8"Press any key to exit"s, ConsoleForeground::DARK_GRAY);
Console::PauseAny();
输出
Original: Hello ? █ StrLength: 10 █ UTF8Chars: 7 █ Padded:Hello ? █ PadLeft with char padding
Original: Hello ? █ StrLength: 10 █ UTF8Chars: 7 █ Padded:@@@@@Hello ? █ PadLeft with char padding
Original: Hello ? █ StrLength: 10 █ UTF8Chars: 7 █ Padded:Hello ? █ PadRight with char padding
Original: Hello ? █ StrLength: 10 █ UTF8Chars: 7 █ Padded:Hello ?@@@@@ █ PadRight with char padding
Original: Hello ? █ StrLength: 10 █ UTF8Chars: 7 █ Padded:Hello ? █ PadLeft with string padding
Original: Hello ? █ StrLength: 10 █ UTF8Chars: 7 █ Padded:<<><>Hello ? █ PadLeft with string padding
Original: Hello ? █ StrLength: 10 █ UTF8Chars: 7 █ Padded:Hello ? █ PadRight with string padding
Original: Hello ? █ StrLength: 10 █ UTF8Chars: 7 █ Padded:Hello ?<><>< █ PadRight with string padding
Original: Hello ? █ StrLength: 10 █ UTF8Chars: 7 █ Padded:Hello ? █ PadLeftUTF8 with char padding
Original: Hello ? █ StrLength: 10 █ UTF8Chars: 7 █ Padded:@@@@@@@@Hello ? █ PadLeftUTF8 with char padding
Original: Hello ? █ StrLength: 10 █ UTF8Chars: 7 █ Padded:Hello ? █ PadRightUTF8 with char padding
Original: Hello ? █ StrLength: 10 █ UTF8Chars: 7 █ Padded:Hello ?@@@@@@@@ █ PadRightUTF8 with char padding
Original: Hello ? █ StrLength: 10 █ UTF8Chars: 7 █ Padded:Hello ? █ PadLeftUTF8 with string padding
Original: Hello ? █ StrLength: 10 █ UTF8Chars: 7 █ Padded:????????Hello ? █ PadLeftUTF8 with string padding
Original: Hello ? █ StrLength: 10 █ UTF8Chars: 7 █ Padded:Hello ? █ PadRightUTF8 with string padding
Original: Hello ? █ StrLength: 10 █ UTF8Chars: 7 █ Padded:Hello ????????? █ PadRightUTF8 with string padding
使用新的Windows Terminal 可以绘制 unicode glyps-emoticons。将 Microsoft Visual C++ 编译器与 Visual Studio + /std:c++17 + /utf-8 一起使用：
使用经典的控制台cmd.exe画不好
repl.it 中的输出，使用 Linux + Clang + std=c++17 https://repl.it/@JomaCorpFX/Padding#main.cpp
【讨论】：
【参考方案11】：我正在寻找这个主题，因为我正在开发 VCL；无论如何，制作一个函数并不是那么难。
void addWhiteSpcs(string &str, int maxLength)
int i, length;
length = str.length();
for(i=length; i<maxLength; i++)
str += " ";
;
string name1 = "johnny";
string name2 = "cash";
addWhiteSpcs(name1, 10);
addWhiteSpcs(name2, 10);
在这两种情况下，它都会在右侧添加 10 个空格。我建议使用 courier 或 consolas 等等宽字体以获得正确的格式。
当您不使用等宽字体时会发生这种情况 约翰尼___ 现金______
// using monospace font the output will be
johnny____
cash______
两种情况的长度相同。
【讨论】：
【参考方案12】：如果您想在不使用流的情况下进行填充：
std::size_t pad_size = 10, value = 123;
std::string t = std::string(pad_size , ' ') + std::to_string(value);
std::string padded = t.substr(std::min(t.size() - pad_size, pad_size));
Try it online!
【讨论】：
【参考方案13】：这个怎么样：
const int column_len = 50;
string s;
s = "....some value ... ";
int fill_pad = column_len - s.length();
std::cout << s << std::setw(fill_pad) << " Second column " << other_field << std::endl;
【讨论】：
【参考方案14】：创建一个包含 10 个空格的新字符串，并在两个字符串中向后工作。
string padstring(const string &source, size_t totalLength, char padChar)
if (source.length() >= totalLength)
return source;
string padded(totalLength, padChar);
string::const_reverse_iterator iSource = source.rbegin();
string::reverse_iterator iPadded = padded.rbegin();
for (;iSource != source.rend(); ++iSource, ++iPadded)
*iPadded = *iSource;
return padded;
【讨论】：
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