如何在 C++ 中对齐用户输入（不使用 iomanip）

简单快速。但你应该明白。

#include <cstdlib>
#include <string>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <algorithm>

std::string get_text(std::istream &is = std::cin)
{
    std::string text;

    for(std::string line; std::cout << "> ", std::getline(is, line) && !line.empty(); text += ' ' + line);

    return text;
}

enum alignment_t { align_left, align_right, align_center };
alignment_t const align_choices[]{ align_left, align_right, align_center };
char const *align_choices_strings[]{ "Left", "Right", "Center" };

std::string extract_line(std::stringstream &ss, int max_width)
{
    std::string line;
    std::string word;
    while ((ss >> word) && line.length() + word.length() + 1 <= max_width)
        line += word + ' ';

    if(line.length())
        line.pop_back();

    if (line.length() + word.length() + 1 >= max_width) {
        std::stringstream temp;
        temp << word;
        temp << ss.rdbuf();
        ss.swap(temp);
    }

    return line;
}

void print_box(std::string const &text, int width, alignment_t alignment = align_left, std::ostream &os = std::cout)
{
    for (int i = 1; i <= width; ++i)
        os << i % 10;
    os << '\n';

    os << '+' << std::setw(width) << std::setfill('-') << "+\n";

    std::stringstream ss;
    ss.str(text);

    for (std::string line{ extract_line(ss, width - 2) }; line.length(); line = extract_line(ss, width - 2)) {

        os << std::setw(1) << '|' << std::setw(width - 2) << std::setfill(' ');

        switch (alignment) {
        case align_left:
            os << std::left << line << std::setw(1) << "|\n";;
            break;

        case align_right:
            os << std::right << line << std::setw(1) << "|\n";;
            break;

        case align_center:
        {
            int fill = (width - line.length()) / 2;
            os << std::setw(fill + line.length()) << std::right << line << std::setw(width - line.length() - fill) << "|\n";
            break;
        }
        }
    }

    os << std::setw(1) << '+' << std::setw(width) << std::setfill('-') << std::right << "+\n";
}

int main()
{
    std::cout << "Enter text, empty return will quit the input\n";
    auto text{ get_text() };

    std::cout << "> Enter width of text and align(Left, Right, Center): ";
    int width;
    std::string alignment;
    auto alignment_choice{ std::cbegin(align_choices_strings) };

    if (!(std::cin >> width >> alignment) ||
        (alignment_choice = std::find(std::cbegin(align_choices_strings), std::cend(align_choices_strings), alignment))
        == std::cend(align_choices_strings))
    {
        std::cerr << "Input error.\n\n";
        std::cout << "Bye.\n\n";
        return EXIT_FAILURE;
    }

    print_box(text, width, align_choices[alignment_choice - std::cbegin(align_choices_strings)]);
}

试运行：

Enter text, empty return will quit the input
> The journey began at
> Folly Bridge near Oxford
> and ended five miles away
> in the village of
> Godstow. During the trip
> Charles Dodgson told the
> girls a story that
> featured a bored little
> girl named Alice who goes
> looking for an adventure.
>
> Enter width of text and align(Left, Right, Center): 25 Right
+-----------------------+
|   The journey began at|
| Bridge near Oxford and|
| five miles away in the|
| of Godstow. During the|
|   Charles Dodgson told|
|     girls a story that|
|    a bored little girl|
| Alice who goes looking|
+-----------------------+

Enter text, empty return will quit the input
> The journey began at
> Folly Bridge near Oxford
> and ended five miles away
> in the village of
> Godstow. During the trip
> Charles Dodgson told the
> girls a story that
> featured a bored little
> girl named Alice who goes
> looking for an adventure.
>
> Enter width of text and align(Left, Right, Center): 30 Center
+----------------------------+
|  The journey began at Folly|
|  near Oxford and ended five|
|    away in the village of  |
|   During the trip Charles  |
| told the girls a story that|
|  a bored little girl named |
+----------------------------+

Enter text, empty return will quit the input
> The journey began at
> Folly Bridge near Oxford
> and ended five miles away
> in the village of
> Godstow. During the trip
> Charles Dodgson told the
> girls a story that
> featured a bored little
> girl named Alice who goes
> looking for an adventure.
>
> Enter width of text and align(Left, Right, Center): 40 Left
+--------------------------------------+
|The journey began at Folly Bridge     |
|Oxford and ended five miles away in   |
|village of Godstow. During the trip   |
|Dodgson told the girls a story that   |
|a bored little girl named Alice who   |
+--------------------------------------+

修复了代码 - 不再吞下单词和最后一行。但我拒绝为示例输出重新运行它树时间。