Reducing the number of repeating same strings or integers to 1-CodePudding

Initial

 list = { null, 1, 2, null, null, null, 4, 5, 6 };

Expecatiton

 list = { null, 1, 2, null, 4, 5, 6 };

CodePudding user response：

If list is an obsolete ArrayList or List<oblect> you can try a simple for loop:

var list = new ArrayList { null, 1, 2, null, null, null, 4, 5, 6 };

int index = 0;

// Remove consequent null's
for (int i = 1; i < list.Count;   i)
    if (list[i] != null || list[index] != null)
        list[index  ] = list[i];

list.RemoveRange(index, list.Count - index);

To get rid of duplicates

int index = 0;

for (int i = 1; i < list.Count;   i)
    if (list[i] != list[index])
        list[index  ] = list[i];

list.RemoveRange(index, list.Count - index);

CodePudding user response：

When you are removing items from a list, loop it backwards, so that the indexes of the not yet processed items remains the same.

if (list.Count >= 2) {
    for (int i = list.Count - 1; i > 0; i--) {
        if (list[i] == list[i - 1]) {
            list.RemoveAt(i);
        }
    }
}