Question

考虑3个例子：

功能（[＆＃34; a＆＃34;]） - ＆gt;结果=＆＃34; a＆＃34;，
功能（[＆＃34; a＆＃34;，＆＃34; b＆＃34;]） - ＆gt; result =＆＃34; a和b＆＃34;，
功能（[＆＃34; a＆＃34;，＆＃34; b＆＃34;，＆＃34; c＆＃34;]） - ＆gt;结果=＆＃34; a，b和c＆＃34;

是否有比以下更优雅或更有效的方法：

result = fieldList.Aggregate((a, b) => a.Replace(" and ", ", ") + " and " + b);

我假设fiedlList至少有一个元素。

或传统节目：

StringBuilder sb = new StringBuilder();
for(int i = 0; i < fieldList.Count; i++)
{
    string field = fieldList[i];
    if (i == 0)
         sb.Append(field);
    else if (i == fieldList.Count - 1)
        sb.AppendFormat(" and {0}", field);
    else
        sb.AppendFormat(", {0}", field);
}
result = sb.ToString();

我看不到top选项中的StringBuilder会起作用。

我想到的唯一另一种方法是首先删除最后一个元素，然后在末尾追加：

var last = fieldList.Last();
fieldList.RemoveAt(fieldList.Count - 1);
result = fieldList.Aggregate(new StringBuilder(), (sb, f) => { 
    if (sb.Length == 0) 
        sb.Append(f); 
    else
        sb.AppendFormat(", {0}", f);
    return sb;
}).ToString();
if (result.Length > 0)
    result += " and " + last;
else
    result = last;

Answer 1

从@BikalBhattarai建议和@Darren在该帖子中发表的评论中被盗：

result = String.Join(", ", fieldList.ToArray(), 0, fieldList.Count - 1); 
if (fieldList.Count > 1) 
    result += " and " + fieldList.Last();

Answer 2

这对我有用：

var result = String.Join(" and ", new []
{
    String.Join(", ", fieldList.Take(fieldList.Length - 1)),
    fieldList.LastOrDefault()
}.Where(x => x != null));

它甚至适用于空数组。

Answer 3

其他解决方案

void Tokenize(const string& str,vector<string>& tokens, const string& delim)
{
       // Skip delimiters at beginning.
     string::size_type lastPos = str.find_first_not_of(delimiters, 0);
     // Find first "non-delimiter".
     string::size_type pos     = str.find_first_of(delimiters, lastPos);

while (string::npos != pos || string::npos != lastPos)
 {
    // Found a token, add it to the vector.
    tokens.push_back(str.substr(lastPos, pos - lastPos));
    // Skip delimiters.  Note the "not_of"
    lastPos = str.find_first_not_of(delimiters, pos);
    // Find next "non-delimiter"
    pos = str.find_first_of(delimiters, lastPos);
  }
}

c＃linq csv更改最后一个元素的分隔符

3 个答案: