Here I have a string list as follows:

List<string> str = new List<string> 
{ "1", "22", "3", "44", "55", "666666", "7777777", "8", "99" };

What I want is merging short strings into a long string of length less than n.

Expect:

n = 5
newlist = { "1223", "4455", "666666", "7777777", "899" };

CodePudding user response：

void Main()
{
    List<string> str = new() { "1", "22", "3", "44", "55", "666666", "7777777", "8", "99" };
    
    const int n = 5;
    
    List<string> newList = new();
    
    var newString = string.Empty;
    foreach (var s in str)
    {
        if ((newString.Length   s.Length) <= n)
        {
            newString  = s;
            continue;
        }
        newList.Add(newString);
        newString = s;
    }
    
    newList.Add(newString); // Don't forget the last under length string
    Console.WriteLine(newList);
}

// Outputs  "1223", "4455", "666666", "7777777", "899"
// Also handles empty input strings

CodePudding user response：

Late to the answer. LINQ .Aggregate() is alternative solution for foreach loop.

The .Aggregate() is able to use to iterate with the current value and next value.

1. Check toBeAppended value.

   1.1 If toBeAppended.Length > n, add the current value to the result. And you need to reset the current value.

   1.2 Else set the current with toBeAppended.

2. After the end of the interaction, make sure you need to add the last value to the result.

List<string> str = new List<string> { "1", "22", "3", "44", "55", "666666", "7777777", "8", "99" };
int n = 5;
var result = new List<string>();
        
var last = str.Aggregate("",
        (current, next) => 
        {
            var toBeAppended = current   next;
                        
            if (toBeAppended.Length >= n)
            {
                result.Add(current);
                current = next;
            }
            else
            {
                current = toBeAppended;
            }
                        
            return current; 
        });
        
result.Add(last);

Sample Program