c# - 如何将每个句子的第一个字符大写

Question

使用接受字符串作为参数的方法创建一个应用程序，并返回字符串的副本，每个句子的第一个字符大写。

这是我到目前为止所要做的，但我似乎做对了:

    //Create method to process string.
    private string Sentences(string input)
    {
        //Capitalize first letter of input.
        char firstLetter = char.ToUpper(input[0]);

        //Combine the capitalize letter with the rest of the input.
        input = firstLetter.ToString() + input.Substring(1);

        //Create a char array to hold all characters in input.
        char[] letters = new char[input.Length];

        //Read the characters from input into the array.
        for (int i = 0; i < input.Length; i++)
        {
            letters[i] = input[i];
        }

        //Loop through array to test for punctuation and capitalize a character 2 index away.
        for (int index = 0; index < letters.Length; index++)
        {
            if(char.IsPunctuation(letters[index]))
            {
                if (!((index + 2) >= letters.Length))
                {
                    char.ToUpper(letters[index+ 2]);
                }
            }
        }

        for(int ind = 0; ind < letters.Length; ind++)
        {
            input += letters[ind].ToString();
        }

        return input;
    }

Answer 1

您可以使用 Linq.Aggregate n - 查看代码和代码输出中的注释以了解其工作原理。

这个也符合“Bla.blubb”——你需要检查“.?!”之后的空格

using System;
using System.Linq;

internal class Program
{
    static string Capitalize(string oldSentence )
    {
        return

            // this will look at oldSentence char for char, we start with a
            // new string "" (the accumulator, short acc)
            // and inspect each char c of oldSentence

            // comment all the Console.Writelines in this function, thats 
            // just so you see whats done by Aggregate, not needed for it to 
            // work

            oldSentence 
            .Aggregate("", (acc, c) =>
             {
                 System.Console.WriteLine("Accumulated: " + acc);
                 System.Console.WriteLine("Cecking:     " + c);

                 // if the accumulator is empty or the last character of 
                 // trimmed acc is a ".?!" we append the
                 // upper case of c to it
                 if (acc.Length == 0 || ".?!".Any(p => p == acc.Trim().Last())) // (*)
                     acc += char.ToUpper(c);
                 else
                     acc += c; // else we add it unmodified

                 System.Console.WriteLine($"After:      {acc}\n");

                 return acc; // this returns the acc for the next iteration/next c                  
            });
    }

    static void Main(string[] args)
    {
        Console.SetBufferSize(120, 1000);
        var oldSentence = "This is a testSentence. some occurences "
            + "need capitalization! for examlpe here. or here? maybe "
            + "yes, maybe not.";

        var newSentence = Capitalize(oldSentence);

        Console.WriteLine(new string('*', 80));
        Console.WriteLine(newSentence);
        Console.ReadLine();
    }
}

(*)

• ".?!".Any(p => p == ... )) 表示字符串 ".?!" 包含等于的任何字符...
• acc.Trim().Last() 表示:删除 acc 前端/末尾的空格并给我最后一个字符

.Last() 和 .Any() 也是 Linq。大多数 Linq-esc 扩展都可以在这里找到: https://msdn.microsoft.com/en-us/library/9eekhta0(v=vs.110).aspx

输出(被截断 - 它相当长;o)

Accumulated:
Cecking:     T
After:      T

Accumulated: T
Cecking:     h
After:      Th

Accumulated: Th
Cecking:     i
After:      Thi

Accumulated: Thi
Cecking:     s
After:      This

Accumulated: This
Cecking:
After:      This

Accumulated: This
Cecking:     i
After:      This i

Accumulated: This i
Cecking:     s
After:      This is

<snipp - .. you get the idea how Aggregate works ...>

Accumulated: This is a testSentence.
Cecking:     s
After:      This is a testSentence. S

<snipp>

Accumulated: This is a testSentence. Some occurences need capitalization!
Cecking:     f
After:      This is a testSentence. Some occurences need capitalization! F

<snipp> 
********************************************************************************
This is a testSentence. Some occurences need capitalization! For examlpe here. Or here? Maybe yes, maybe not.