[C#] 대소 문자를 무시하고 String.Replace

2.5X FASTER 및 MOST EFFECTIVE 방법은 다른 정규식 방법보다 :

/// <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();

}

참고 :에StringComparison.OrdinalIgnoreCase 대한 매개 변수로 case == 를 무시하십시오StringComparison comparisonType . 모든 값을 바꾸는 가장 빠르고 대소 문자를 구분하지 않는 방법입니다.

이 방법의 장점 :

• 높은 CPU 및 메모리 효율성;
• 정규식을 사용하는 다른 방법보다 2.5 배 빠른 가장 빠른 솔루션입니다.
• 입력 문자열에서 부품을 제거하는 데 적합합니다 (로 설정 newValue됨
  null).
• 원본 .NET C # string.Replace 동작과 동일하지만 예외는 동일합니다.
• 잘 설명되고 이해하기 쉽다.
• 더 단순 – 정규식이 없습니다. 정규 표현식은 다양성 때문에 컴파일 속도가 느립니다.
• 이 방법은 잘 테스트되었으며 다른 솔루션의 무한 루프와 같은 숨겨진 결함은 없으며 등급도 높습니다.

@ AsValeO : Regex 언어 요소와 함께 작동하지 않으므로 보편적 인 방법이 아닙니다.

@ Mike Stillion :이 코드에 문제가 있습니다. new의 텍스트가 이전 텍스트의 수퍼 세트 인 경우 무한 루프가 발생할 수 있습니다.

벤치 마크 방지 :이 솔루션은 @Steve B.의 정규식보다 2.59 배 빠릅니다.

// 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();

독창적 인 아이디어 – @ Darky711; 에 @MinerR 감사합니다 StringBuilder.

답변

static public class StringExtensions
{
    static public string ReplaceInsensitive(this string str, string from, string to)
    {
        str = Regex.Replace(str, from, to, RegexOptions.IgnoreCase);
        return str;
    }
}

public static string Replace(this string str, string old, string @new, StringComparison comparison)
{
    @new = @new ?? "";
    if (string.IsNullOrEmpty(str) || string.IsNullOrEmpty(old) || old.Equals(@new, comparison))
        return str;
    int foundAt = 0;
    while ((foundAt = str.IndexOf(old, foundAt, comparison)) != -1)
    {
        str = str.Remove(foundAt, old.Length).Insert(foundAt, @new);
        foundAt += @new.Length;
    }
    return str;
}

Replace(sourceString, "replacethis", "withthis", , , CompareMethod.Text)

string myString = "find Me and replace ME";
string strReplace = "me";
myString = Regex.Replace(myString, "me", strReplace, RegexOptions.IgnoreCase);