为什么我使用 StringBuilder 和 .replace 会得到意想不到的结果？

Question

我正在尝试在字符串 (wildCard) 中查找特定条件 (dogsWildcard、catsWildcard、birdsWildcard)，然后修改该字符串，使其具有与条件关联的数字。

比如我要冷到下面return："*DOGS 111 *CATS 222 *BIRDS 333"

但是，它 return 看起来像："*CATS *DOGS 222 *BIRDS*DOGS 111 *EVENTS *BIRDS*BIRDS *DOGS *CATS 333"


public string ProcessMerchantRefNbr()
{
var wildCard = "*DOGS *CATS *BIRDS";

string catsWildcard = "*CATS";
string dogsWildcard = "*DOGS";
string birdsWildcard = "*BIRDS";

var dogId = "111";
var catId = "222";
var birdId = "333";

var strMerchantRefNbr = new StringBuilder();

if (wildCard.Contains(catsWildcard)) strMerchantRefNbr.Append($"{catsWildcard} {wildCard.Replace(catsWildcard, catId)}");

if (wildCard.Contains(dogsWildcard)) strMerchantRefNbr.Append($"{dogsWildcard} {wildCard.Replace(dogsWildcard, dogId)}");

if (wildCard.Contains(birdsWildcard)) strMerchantRefNbr.Append($"{birdsWildcard} {wildCard.Replace(birdsWildcard, birdId)}");

return strMerchantRefNbr.ToString()
}

我做错了什么？

Answer 1

只是你不需要 Replace.

var strMerchantRefNbr = new StringBuilder();

if (wildCard.Contains(catsWildcard)) strMerchantRefNbr.Append($"{catsWildcard} {catId} ");
if (wildCard.Contains(dogsWildcard)) strMerchantRefNbr.Append($"{dogsWildcard} {dogId} ");
if (wildCard.Contains(birdsWildcard)) strMerchantRefNbr.Append($"{birdsWildcard} {birdId} ");

// strMerchantRefNbr.ToString(): *CATS 222 *DOGS 111 *BIRDS 333

Answer 2

试试这个

public string ProcessMerchantRefNbr()
{
    var wildCard = "*DOGS *CATS *BIRDS";
    string[,] replacements = new string[,] { { "*DOGS", "*CATS", "*BIRDS" }, 
                                             { "111", "222", "333" } };

    var sb = new StringBuilder(wildCard);

    for (var i = 0; i <= replacements.GetLength(0); i++)
    {
        var wc = replacements[0, i];
        var num = replacements[1, i];

        sb.Replace(wc, wc + " " + num);
    }

    return sb.ToString();
}

结果

*DOGS 111 *CATS 222 *BIRDS 333

或者我会更灵活地创建这样的东西

string[,] replacements = new string[,] { { "*DOGS", "*CATS", "*BIRDS" }, 
{ "*DOGS 111 ...", "*CATS 222 ...", "*BIRDS 333 ..." } };

Answer 3

您正在为每个解析为 true 的条件附加一个替换字符串。实际上你可以省略检查 - 将原始字符串附加到构建器并在其上使用 Replace:

var strMerchantRefNbr = new StringBuilder();
strMerchantRefNbr.Append(wildCard);
strMerchantRefNbr.Replace(catsWildcard, $"{catsWildcard} {catId}");
strMerchantRefNbr.Replace(dogsWildcard, $"{dogsWildcard} {dogId}");
strMerchantRefNbr.Replace(birdsWildcard, $"{birdsWildcard} {birdId}");

可以通过创建通配符 -> 替换对和使用循环来改进此代码。例如使用值元组：

var replacements = new List<(string Wildcard, string Replacement)> 
{
    ("*CATS", "111"),
    ("*DOGS", "222"),
    ("*BIRDS", "333")
};

var strMerchantRefNbr = new StringBuilder();
strMerchantRefNbr.Append(wildCard);
foreach(var (wc, replacement) in replacements)
{
    strMerchantRefNbr.Replace(wc, $"{wc} {replacement}");
}

为什么我使用 StringBuilder 和 .replace 会得到意想不到的结果？

Why am I getting unexpected results with StringBuilder and .replace?

c#

stringbuilder

replace