爲什麼這個列表只打印出最後一個字符？

Question

所以我一直在研究這個程序分析某個輸入文件，除了關鍵字列表之外，幾乎所有東西都正確輸出。

關於繼承人的關鍵字列表和相關功能的代碼片段：

public class Token //Token structure to be added for each Token in the tokenTable 
{ 
    public string value; 
    public string type; 
} 

internal static class Define_input_output 
{ 
    public const string inFile = "input.txt"; //set file to read 
    public const string outFile = "output.txt"; //set file to write to 
} 

public static void placeKeywords_in_keywordsTable(List<string> keywords, List<Token> keywordTable) 
{ 
    Token newToken = new Token(); 

    for (int i = 0; i < keywords.Count; i++) //loop through each keyword 
    { 
     newToken.value = keywords[i]; //add keyword[i] to newToken's value 
     newToken.type = "KW"; //assign "kw" to newToken's type 
     keywordTable.Add(newToken); //push newToken to keywordTable 
    } 
} 

public static void print_Tables_to_outputFile(StreamWriter output, List<Token> keywordTable) 
{ 
    output.Write("\r\n"); 
    output.Write("-".PadRight(21, '-')); 
    output.Write("\r\n"); 
    output.Write(' '); 
    output.Write("Keyword ".PadRight(11)); 
    output.Write("|".PadRight(2)); 
    output.Write("Index"); 
    output.Write("\r\n"); 
    output.Write("-".PadRight(21, '-')); 
    output.Write("\r\n"); 

    for (int i = 0; i < keywordTable.Count; i++) //loop through each element in keywordTable 
    { 
     output.Write(' '); 
     output.Write((keywordTable[i].value).PadRight(10)); 
     output.Write(" |".PadRight(7)); 
     output.Write(i); 
     output.Write("\r\n"); 
    } 
} 

static int Main() 
{ 
    StreamReader input = new StreamReader(Define_input_output.inFile);//input file 
    StreamWriter output = new StreamWriter(Define_input_output.outFile);//output file 

    List<string> keywords = new List<string>() { "else", "if", "int", "return", "void", "while", "+", "-", "*", "/", "<", "<=", ">", ">=", "==", "!=", "=", ";", ",", "(", ")", "[", "]", "{", "}", "/*", "*/" }; 
    List<Token> keywordTable = new List<Token>(); 

    placeKeywords_in_keywordsTable(keywords, keywordTable); //place all the keywords into keywordTable 

    while (!input.EndOfStream) //read each line until end of file 
    { 
     read_inputFile(input, output, keywordTable); 
    } 

    print_Tables_to_outputFile(output, keywordTable); 

    input.Close(); //close input file 
    output.Close(); //close output file 

    return 0; 
} 

問題IM具有隻是這個「* /」字符被打印出來的關鍵詞表。其索引26次（這是索引的正確數量，因爲這是多少個字符在列表中）。 我通過從列表中刪除最後兩個字符進行測試，並且「}」字符開始打印26次。

我不知道有什麼缺失，因爲我仔細查看了代碼多次，我只是無法找到問題所在。 任何幫助表示讚賞。謝謝！

Answer 1

的問題是在你的placeKeywords_in_keywordsTable方法。您只需初始化Token一次，然後在每次更新循環的循環中進行更新。所以基本上你只剩最後keyword

更改爲：

for (int i = 0; i < keywords.Count; i++) //loop through each keyword 
{ 
    Token newToken = new Token(); 
    newToken.value = keywords[i]; //add keyword[i] to newToken's value 
    newToken.type = "KW"; //assign "kw" to newToken's type 
    keywordTable.Add(newToken); //push newToken to keywordTable 
} 

一個更好的辦法是使用這種形式的初始化的：

for (int i = 0; i < keywords.Count; i++) //loop through each keyword 
{ 
    Token newToken = new Token 
    { 
     value = keywords[i], 
     type = "KW" 
    }; 
    keywordTable.Add(newToken); //push newToken to keywordTable 
} 

更好的將是使用foreach而不是一個for：

foreach(var i in keywords) 
{ 
    Token newToken = new Token 
    { 
     value = i, 
     type = "KW" 
    }; 
    keywordTable.Add(newToken); 
} 

如果你想用linq做：

keywordTable = keywords.Select(item => new Token { value = item, type = "KW" }).ToList();