c# - 在一个字符前查找 10 个字符

Question

如何在字符串中的字符之前找到 10 个字符？例如;

string abcd = "asdsdasdasdasdasdasasdasasdssXsdasdsadas";

如何在 X 之前找到 10 个字符？

Answer 1

string searchWithinThis = "asdsdasdasdasdasdasasdasasdssXsdasdsadas";
string searchForThis = "X";

int firstCharacter = searchWithinThis.IndexOf(searchForThis);

if (firstCharacter < 0) {
  Console.WriteLine("Character {0} not found", searchForThis);
} else {
  Console.WriteLine("First occurrence: {0}", firstCharacter);
}

如果您想要 X 之前的 10 个字符，包括 X：

int tenCharactersBefore = Math.Max(firstCharacter - 10, 0);

string result = searchWithinThis.SubString(tenCharactersBefore, 10)
Console.WriteLine("The ten characters before are {0}", result);

如果你想要 X 之前的 10 个字符的字符串，不包括 X：

int tenCharactersBefore = Math.Max(firstCharacter - 11, 0);

string result = searchWithinThis.SubString(tenCharactersBefore, 10)
Console.WriteLine("The ten characters before are {0}", result);

如果您只想要 X 之前 10 个字符的字符：

int tenCharactersBefore = Math.Max(firstCharacter - 10, 0);

string result = searchWithinThis.SubString(tenCharactersBefore, 1)
Console.WriteLine("The ten characters before are {0}", result);

Answer 2

您可以使用String.Substring和String.IndexOf方法，例如；

string abcd = "asdsdasdasdasdasdasasdasasdssXsdasdsadas";
Console.WriteLine(abcd.Substring(abcd.IndexOf("X") - 10, 10));

基本上，您获得该位置的索引X并减去10该位置，之后，您将获得从该位置开始的子字符串并在10其后获取字符。

当然，您应该首先检查X's 的索引是否大于10或不大于。因为如果小于10，你应该检查；

if(abcd.IndexOf("X") < 10)
    Console.WriteLine(abcd.Substring(0, abcd.IndexOf("X")));
else
    Console.WriteLine(abcd.Substring(abcd.IndexOf("X") - 10, 10));

输出将是；

asdasasdss

这是一个DEMO.

Answer 3

 string result=string.Empty;
 string abcd = "asdsdasdasdasdasdasasdasasdssXsdasdsadas";

    int indexOfStringToSearch = abcd.IndexOf("X");
    if(indexOfStringToSearch!=-1)
      { 
        if(indexOfStringToSearch -10 >0)
            result = abcd.Substring(indexOfStringToSearch-10,10);
        else
            result = abcd.Substring(0,indexOfStringToSearch-1);
     }

Answer 4

如果只有一个“X”字符：

尝试这个：

string abcd = "asdsdasdasdasdasdasasdasasdssXsdasdsadas";
string[] words = s.Split('X');
Console.WriteLine(words[0].substring(words[0].length-10,10));

或多个

string abcd = "asdsdasdasdasdasdasasdasasdssXsdasdsadas";
string[] words = s.Split('X');
for(int i=0;i<words.length; i++)
{
   Console.WriteLine(word[i].substring(word[i].length-10,10));
}