How to check if string contains single occurence of substring?

Question

I have this:

string strings = "a b c d d e";

And I need something similar to string.Contains() , but I need to know not only whether a string is present (in case above a letter), but also if it is present only ONE SINGLE time .

How can I achieve this?

Answer 1

You can use LastIndexOf(String) and IndexOf(String) and verify that the values returned are equal. Of course also check if the String is found at all(ie the returned value is not -1).

Answer 2

您可以使用LINQ

int count = strings.Count(f => f == 'd');

Answer 3

替代

if(Regex.Matches(input,Regex.Escape(pattern)).Count==1)

Answer 4

try like below... it will help you...

string strings = "a b c d d e";
string text ="a";
int count = 0;
int i = 0;
while ((i = strings.IndexOf(text, i)) != -1)
{
    i += text.Length;
    count++;
}
if(count == 0)
Console.WriteLine("String not Present");

if(count == 1)
Console.WriteLine("String Occured Only one time");

if(Count>1)
Console.WriteLine("String Occurance : " + count.Tostring());

Answer 5

    string source = "a b c d d e";
    string search = "d";
    int i = source.IndexOf(search, 0);
    int j = source.IndexOf(search, i + search.Length);
    if (i == -1)
        Console.WriteLine("No match");
    else if (j == -1)
        Console.WriteLine("One match");   
    else
        Console.WriteLine("More match");

Answer 6

另一种简单的选择

if(strings.Split(new [] { "a" }, StringSplitOptions.None).Length == 2)

Answer 7

You can check the length (minus 1) of the array myString.Split('a') assuming that you're searching for the occurrences of 'a'