我在 c# winforms 中做了一个项目。
我想在 csv 中获取第一列值。
var reader = new StreamReader(File.OpenRead(@"C:\test.csv"));
List<string> listA = new List<string>();
List<string> listB = new List<string>();
while (!reader.EndOfStream)
{
var line = reader.ReadLine();
var values = line.Split(';');
listA.Add(values[0]);
}
------------------
no |name |
------------------
1 |wwwwww
2 |yyyyy
3 |aaaaa
4 |bbbbbb
现在我正在使用上面的代码。它逐行给出值。我想要 listA 中的所有名称值
有人知道吗？
Some frown upon Regex but I think it provides good flexibility. Here is an example inspired by Adrian Mejia. Basically, you can choose particular characters between which the delimiter is valid in the context. i.e. a comma in "hello, world" or 'hello, world' would be valid.
static void Main(string[] args)
{
string csv = "Hello,1,3.5,25,\"speech marks\",'inverted commas'\r\nWorld,2,4,60,\"again, more speech marks\",'something else in inverted commas, with a comma'";
// General way to create grouping constructs which are valid 'text' fields
string p = "{0}([^{0}]*){0}"; // match group '([^']*)' (inverted commas) or \"([^\"]*)\" (speech marks)
string c = "(?<={0}|^)([^{0}]*)(?:{0}|$)"; // commas or other delimiter group (?<=,|^)([^,]*)(?:,|$)
char delimiter = ','; // this can be whatever delimiter you like
string p1 = String.Format(p, "\""); // speechmarks group (0)
string p2 = String.Format(p, "'"); // inverted comma group (1)
string c1 = String.Format(c, delimiter); // delimiter group (2)
/*
* The first capture group will be speech marks ie. "some text, "
* The second capture group will be inverted commas ie. 'this text'
* The third is everything else seperated by commas i.e. this,and,this will be [this][and][this]
* You can extend this to customise delimiters that represent text where a comma between is a valid entry eg. "this text, complete with a pause, is perfectly valid"
*
* */
//string pattern = "\"([^\"]*)\"|'([^']*)'|(?<=,|^)([^,]*)(?:,|$)";
string pattern = String.Format("{0}|{1}|{2}", new object[] { p1, p2, c1 }); // The actual pattern to match based on groups
string text = csv;
// If you're reading from a text file then this will do the trick. Uses the ReadToEnd() to put the whole file to a string.
//using (TextReader tr = new StreamReader("PATH TO MY CSV FILE", Encoding.ASCII))
//{
// text = tr.ReadToEnd(); // just read the whole stream
//}
string[] lines = text.Split(new char[] { '\r', '\n' }, StringSplitOptions.RemoveEmptyEntries); // if you have a blank line just remove it?
Regex regex = new Regex(pattern, RegexOptions.Compiled | RegexOptions.CultureInvariant | RegexOptions.IgnoreCase); // compile for speed
List<object> rowsOfColumns = new List<object>();
foreach (string row in lines)
{
List<string> columns = new List<string>();
// Find matches.
MatchCollection matches = regex.Matches(row);
foreach (Match match in matches)
{
for (int ii = 0; ii < match.Groups.Count; ii++)
{
if (match.Groups[ii].Success) // ignore things that don't match
{
columns.Add(match.Groups[ii].Value.TrimEnd(new char[] { delimiter })); // strip the delimiter
break;
}
}
}
// Do something with your columns here (add to List for example)
rowsOfColumns.Add(columns);
}
}
现在可以在不读取整个文件的情况下读取 CSV 中的列。您可以使用一些包装器（例如：LINQ to CSV library），但它们只会“隐藏”读取操作。
是的 - 你目前正在分手；
尝试改用逗号。
顺便说一句，最好使用专用库...
var reader = new StreamReader(File.OpenRead(@"C:\test.csv"));
List<string> listA = new List<string>();
while (!reader.EndOfStream)
{
var line = reader.ReadLine();
string[] dates = line.Split(',');
for (int i = 0; i < dates.Length; i++)
{
if(i==0)
listA.Add(dates[0]);
}
}