使用这个，测试和100%工作!

VB。网

Dim myString As String
Dim oldValue As String
Dim newValue As String

myString = Form1.TextBox1.Text
oldValue = TextBox1.Text
newValue = TextBox2.Text

Dim working As String = myString
Dim index As Integer = working.IndexOf(oldValue, StringComparison.CurrentCultureIgnoreCase)

While index <> -1
    working = working.Remove(index, oldValue.Length)
    working = working.Insert(index, newValue)
    index = index + newValue.Length
    index = working.IndexOf(oldValue, index, StringComparison.CurrentCultureIgnoreCase)
    Form1.TextBox1.Text = working
End While

为c#

private void Button2_Click(System.Object sender, System.EventArgs e)
{
    string myString;
    string oldValue;
    string newValue;

    myString = Form1.TextBox1.Text;
    oldValue = TextBox1.Text;
    newValue = TextBox2.Text;

    string working = myString;
    int index = working.IndexOf(oldValue, StringComparison.CurrentCultureIgnoreCase);

    while (index != -1)
    {
        working = working.Remove(index, oldValue.Length);
        working = working.Insert(index, newValue);
        index = index + newValue.Length;
        index = working.IndexOf(oldValue, index, StringComparison.CurrentCultureIgnoreCase);
        Form1.TextBox1.Text = working;
    }
}

修改了@Darky711的答案，使用传入的比较类型和匹配框架替换命名和xml注释尽可能接近。

/// <summary>
/// Returns a new string in which all occurrences of a specified string in the current instance are replaced with another specified string.
/// </summary>
/// <param name="str">The string performing the replace method.</param>
/// <param name="oldValue">The string to be replaced.</param>
/// <param name="newValue">The string replace all occurrances of oldValue.</param>
/// <param name="comparisonType">Type of the comparison.</param>
/// <returns></returns>
public static string Replace(this string str, string oldValue, string @newValue, StringComparison comparisonType)
{
    @newValue = @newValue ?? string.Empty;
    if (string.IsNullOrEmpty(str) || string.IsNullOrEmpty(oldValue) || oldValue.Equals(@newValue, comparisonType))
    {
        return str;
    }
    int foundAt;
    while ((foundAt = str.IndexOf(oldValue, 0, comparisonType)) != -1)
    {
        str = str.Remove(foundAt, oldValue.Length).Insert(foundAt, @newValue);
    }
    return str;
}

2.5倍比其他正则表达式方法更快和最有效的方法:

/// <summary>
/// Returns a new string in which all occurrences of a specified string in the current instance are replaced with another 
/// specified string according the type of search to use for the specified string.
/// </summary>
/// <param name="str">The string performing the replace method.</param>
/// <param name="oldValue">The string to be replaced.</param>
/// <param name="newValue">The string replace all occurrences of <paramref name="oldValue"/>. 
/// If value is equal to <c>null</c>, than all occurrences of <paramref name="oldValue"/> will be removed from the <paramref name="str"/>.</param>
/// <param name="comparisonType">One of the enumeration values that specifies the rules for the search.</param>
/// <returns>A string that is equivalent to the current string except that all instances of <paramref name="oldValue"/> are replaced with <paramref name="newValue"/>. 
/// If <paramref name="oldValue"/> is not found in the current instance, the method returns the current instance unchanged.</returns>
[DebuggerStepThrough]
public static string Replace(this string str,
    string oldValue, string newValue,
    StringComparison comparisonType)
{

    // Check inputs.
    if (str == null)
    {
        // Same as original .NET C# string.Replace behavior.
        throw new ArgumentNullException(nameof(str));
    }
    if (str.Length == 0)
    {
        // Same as original .NET C# string.Replace behavior.
        return str;
    }
    if (oldValue == null)
    {
        // Same as original .NET C# string.Replace behavior.
        throw new ArgumentNullException(nameof(oldValue));
    }
    if (oldValue.Length == 0)
    {
        // Same as original .NET C# string.Replace behavior.
        throw new ArgumentException("String cannot be of zero length.");
    }
    

    //if (oldValue.Equals(newValue, comparisonType))
    //{
    //This condition has no sense
    //It will prevent method from replacesing: "Example", "ExAmPlE", "EXAMPLE" to "example"
    //return str;
    //}



    // Prepare string builder for storing the processed string.
    // Note: StringBuilder has a better performance than String by 30-40%.
    StringBuilder resultStringBuilder = new StringBuilder(str.Length);



    // Analyze the replacement: replace or remove.
    bool isReplacementNullOrEmpty = string.IsNullOrEmpty(newValue);



    // Replace all values.
    const int valueNotFound = -1;
    int foundAt;
    int startSearchFromIndex = 0;
    while ((foundAt = str.IndexOf(oldValue, startSearchFromIndex, comparisonType)) != valueNotFound)
    {
        
        // Append all characters until the found replacement.
        int charsUntilReplacment = foundAt - startSearchFromIndex;
        bool isNothingToAppend = charsUntilReplacment == 0;
        if (!isNothingToAppend)
        {
            resultStringBuilder.Append(str, startSearchFromIndex, charsUntilReplacment);
        }
        


        // Process the replacement.
        if (!isReplacementNullOrEmpty)
        {
            resultStringBuilder.Append(newValue);
        }
        

        // Prepare start index for the next search.
        // This needed to prevent infinite loop, otherwise method always start search 
        // from the start of the string. For example: if an oldValue == "EXAMPLE", newValue == "example"
        // and comparisonType == "any ignore case" will conquer to replacing:
        // "EXAMPLE" to "example" to "example" to "example" … infinite loop.
        startSearchFromIndex = foundAt + oldValue.Length;
        if (startSearchFromIndex == str.Length)
        {
            // It is end of the input string: no more space for the next search.
            // The input string ends with a value that has already been replaced. 
            // Therefore, the string builder with the result is complete and no further action is required.
            return resultStringBuilder.ToString();
        }
    }
    

    // Append the last part to the result.
    int charsUntilStringEnd = str.Length - startSearchFromIndex;
    resultStringBuilder.Append(str, startSearchFromIndex, charsUntilStringEnd);


    return resultStringBuilder.ToString();

}

注意:忽略case == StringComparison。OrdinalIgnoreCase作为stringcomparisontype的参数。它是替换所有值的最快、不区分大小写的方法。

该方法的优点:

High CPU and MEMORY efficiency; It is the fastest solution, 2.5 times faster than other's methods with regular expressions (proof in the end); Suitable for removing parts from the input string (set newValue to null), optimized for this; Same as original .NET C# string.Replace behavior, same exceptions; Well commented, easy to understand; Simpler – no regular expressions. Regular expressions are always slower because of their versatility (even compiled); This method is well tested and there are no hidden flaws like infinite loop in other's solutions, even highly rated:

@AsValeO: Not适用于Regex语言元素，所以它不是 普遍的方法

这段代码有问题。如果文本为new 是文本的超集，这样可以产生无限循环。

防基准测试:这个解决方案比@Steve B.的regex快2.59倍，代码:

// Results:
// 1/2. Regular expression solution: 4486 milliseconds
// 2/2. Current solution: 1727 milliseconds — 2.59X times FASTER! than regex!

// Notes: the test was started 5 times, the result is an average; release build.

const int benchmarkIterations = 1000000;
const string sourceString = "aaaaddsdsdsdsdsd";
const string oldValue = "D";
const string newValue = "Fod";
long totalLenght = 0;

Stopwatch regexStopwatch = Stopwatch.StartNew();
string tempString1;
for (int i = 0; i < benchmarkIterations; i++)
{
    tempString1 = sourceString;
    tempString1 = ReplaceCaseInsensitive(tempString1, oldValue, newValue);

    totalLenght = totalLenght + tempString1.Length;
}
regexStopwatch.Stop();



Stopwatch currentSolutionStopwatch = Stopwatch.StartNew();
string tempString2;
for (int i = 0; i < benchmarkIterations; i++)
{
    tempString2 = sourceString;
    tempString2 = tempString2.Replace(oldValue, newValue,
        StringComparison.OrdinalIgnoreCase);

    totalLenght = totalLenght + tempString2.Length;
}
currentSolutionStopwatch.Stop();

原创创意- @Darky711;感谢@ miner的StringBuilder。

.Net Core有这个内置的方法: 替换(String, String, StringComparison) Doc。现在我们可以简单地写: “…”。替换("oldValue"， "newValue"， stringcompare . ordinalignorecase)

我的这个方法可以忽略大小写以及只选择整个单词

public static string Replace(this string s, string word, string by, StringComparison stringComparison, bool WholeWord)
{
    s = s + " ";
    int wordSt;
    StringBuilder sb = new StringBuilder();
    while (s.IndexOf(word, stringComparison) > -1)
    {
        wordSt = s.IndexOf(word, stringComparison);
        if (!WholeWord || ((wordSt == 0 || !Char.IsLetterOrDigit(char.Parse(s.Substring(wordSt - 1, 1)))) && !Char.IsLetterOrDigit(char.Parse(s.Substring(wordSt + word.Length, 1)))))
        {
            sb.Append(s.Substring(0, wordSt) + by);
        }
        else
        {
            sb.Append(s.Substring(0, wordSt + word.Length));
        }
        s = s.Substring(wordSt + word.Length);
    }
    sb.Append(s);
    return sb.ToString().Substring(0, sb.Length - 1);
}

用Regex扩展Petrucio的答案。在搜索字符串上转义，并在Steve B的回答中建议转义匹配的组(和一些小的改变，我的口味):

public static class StringExtensions
{
    public static string ReplaceIgnoreCase(this string str, string from, string to)
    {
        return Regex.Replace(str, Regex.Escape(from), to.Replace("$", "$$"), RegexOptions.IgnoreCase);
    }
}

这将产生以下预期结果:

Console.WriteLine("(heLLo) wOrld".ReplaceIgnoreCase("(hello) world", "Hi $1 Universe")); // Hi $1 Universe
Console.WriteLine("heLLo wOrld".ReplaceIgnoreCase("(hello) world", "Hi $1 Universe"));   // heLLo wOrld

然而，如果不执行转义，您将得到以下结果，这不是String的预期行为。替换是不区分大小写的:

Console.WriteLine("(heLLo) wOrld".ReplaceIgnoreCase_NoEscaping("(hello) world", "Hi $1 Universe")); // (heLLo) wOrld
Console.WriteLine("heLLo wOrld".ReplaceIgnoreCase_NoEscaping("(hello) world", "Hi $1 Universe"));   // Hi heLLo Universe