C# 替换字符串中的第一次出现
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Replace the first occurrence in a string
提问by markzzz
I have this string :
我有这个字符串：
Hello my name is Marco
and I'd like to replace the first space (between Helloand my) with <br />. Only the first.
我想用.替换第一个空格（Hello和之间my）<br />。只有第一个。
What's the best way to do it on C#/.NET 3.5?
在 C#/.NET 3.5 上执行此操作的最佳方法是什么？
采纳答案by Marshal
No need to add substrings, following will find the first space instance only. From MSDN:
不需要添加子串，后面只会找到第一个空格实例。从MSDN：
Reports the zero-based index of the first occurrence of the specified string in this instance.
报告此实例中第一次出现指定字符串的从零开始的索引。
string x = "Hello my name is Marco";
int index = x.IndexOf(" ");
x= index >=0 ? x.Insert(index, @"<br />") : x;
Edit:If you are not sure if space will occur, some validations must come into place. I have edit the answer accordingly.
编辑：如果您不确定是否会出现空间，则必须进行一些验证。我已经相应地编辑了答案。
回答by Steve Danner
string tmp = "Hello my name is Marco";
int index = tmp.IndexOf(" ");
tmp = tmp.Substring(0, index) + "<br />" + tmp.Substring(index + 1);
回答by Nikhil Agrawal
string[] str = "Hello my name is Marco".Split(' ');
string newstr = str[0] + "<br /> " + string.Join(" ", str.Skip(1).ToArray());
回答by Jamiec
Here you go, this would work:
给你，这行得通：
var s = "Hello my name is Marco";
var firstSpace = s.IndexOf(" ");
var replaced = s.Substring(0,firstSpace) + "<br/>" + s.Substring(firstSpace+1);
You could make this into an extension method:
你可以把它变成一个扩展方法：
public static string ReplaceFirst(this string input, string find, string replace){
var first= s.IndexOf(find);
return s.Substring(0,first) + replace + s.Substring(first+find.Length);
}
And then the usage would be
然后用法是
var s = "Hello my name is Marco";
var replaced = s.ReplaceFirst(" ","<br/>");
回答by Zaheer Ahmed
public static class MyExtensions
{
public static string ReplaceFirstOccurrance(this string original, string oldValue, string newValue)
{
if (String.IsNullOrEmpty(original))
return String.Empty;
if (String.IsNullOrEmpty(oldValue))
return original;
if (String.IsNullOrEmpty(newValue))
newValue = String.Empty;
int loc = original.IndexOf(oldValue);
return original.Remove(loc, oldValue.Length).Insert(loc, newValue);
}
}
and use it like:
并使用它：
string str="Hello my name is Marco";
str.ReplaceFirstOccurrance("Hello", "<br/>");
str.ReplaceFirstOccurrance("my", "<br/>");
