使用C＃如何在.txt文件中特定行中更改特定字符（基於位置）

Question

enter image description here使用C＃如何在.txt文件中特定行中更改特定字符（基於位置）？

Answer 1

如果你知道行索引，您可以使用：

// Get file content as string array. 
var lines = File.ReadAllLines(filePath); 

var sb = new StringBuilder(lines[lineIndex]); 

// Replacing character at given position 
sb[CharacterIndex] = 'A'; 

lines[lineIndex] = sb.ToString(); 

// Writing new content to file 
File.WriteAllLines(filePath, lines); 

更新（基於新的問題的詳細信息）

你提的問題是關於改變particolar基於串（不是字符）在特定行的位置。您的功能可能是：

void replaceStringAtPosition(string filePath, int lineNumber, int StartingCharacterPosition, int replaceWordLength, string replaceWord) 
{ 
    // Get file content as string array. 
    var lines = File.ReadAllLines(filePath); 

    var sb = new StringBuilder(lines[lineNumber]); 

    if (StartingCharacterPosition > sb.Length - 1) throw new Exception(nameof(StartingCharacterPosition) + " parameter value is greater than line length"); 

    int numberOfCharactersToRemove = StartingCharacterPosition + replaceWordLength > sb.Length - 1 ? sb.Length - StartingCharacterPosition : replaceWordLength; 

    // Replacing string at given position 
    sb.Remove(StartingCharacterPosition, numberOfCharactersToRemove); 
    sb.Insert(StartingCharacterPosition, replaceWord); 

    lines[lineNumber] = sb.ToString(); 

    // Writing new content to file 
    File.WriteAllLines(filePath, lines); 
} 

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