CharEnumerator.MoveNext Method

Definition

Increments the internal index of the current CharEnumerator object to the next character of the enumerated string.

public bool MoveNext ();

Returns

true if the index is successfully incremented and within the enumerated string; otherwise, false.

Implements

Examples

The following example uses the CharEnumerator class to enumerate the individual characters in a string. It instantiates a CharEnumerator object by calling the String.GetEnumerator method, moves from one character to the next by calling the MoveNext method, and displays the current character by retrieving the value of the Current property.

string title = "A Tale of Two Cities";
CharEnumerator chEnum = title.GetEnumerator();
int ctr = 1;
string outputLine1 = null;
string outputLine2 = null;
string outputLine3 = null;

while (chEnum.MoveNext())
{
   outputLine1 += ctr < 10 || ctr % 10 != 0 ? "  " : (ctr / 10) + " ";
   outputLine2 += (ctr % 10) + " ";
   outputLine3 += chEnum.Current + " ";
   ctr++;
}

Console.WriteLine("The length of the string is {0} characters:",
                  title.Length);
Console.WriteLine(outputLine1);
Console.WriteLine(outputLine2);
Console.WriteLine(outputLine3);
// The example displays the following output to the console:
//       The length of the string is 20 characters:
//                         1                   2
//       1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0
//       A   T a l e   o f   T w o   C i t i e s

Note, however, that the same operation can be performed somewhat more intuitively by using foreach (in C#) or For Each (in Visual Basic), as the following example shows.

string title = "A Tale of Two Cities";
int ctr = 1;
string outputLine1 = null;
string outputLine2 = null;
string outputLine3 = null;

foreach (char ch in title)
{
   outputLine1 += ctr < 10 || ctr % 10 != 0 ? "  " : (ctr / 10) + " ";
   outputLine2 += (ctr % 10) + " ";
   outputLine3 += ch + " ";
   ctr++;
}

Console.WriteLine("The length of the string is {0} characters:",
                  title.Length);
Console.WriteLine(outputLine1);
Console.WriteLine(outputLine2);
Console.WriteLine(outputLine3);
// The example displays the following output to the console:
//       The length of the string is 20 characters:
//                         1                   2
//       1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0
//       A   T a l e   o f   T w o   C i t i e s

Remarks

The CharEnumerator class maintains an internal index to the enumerated string, and the MoveNext method increments the index by one. Call MoveNext after calling GetEnumerator or Reset to increment the current character position to the first character in the enumerated string. Check that the return value is true to determine that the current character position is valid.

If the index is already beyond the last character of the enumerated string, the index is not changed and false is returned.

Notice that if the enumerated string is empty (""), the state of the CharEnumerator is always invalid. This is because the internal index for the CharEnumerator is initially before the first character of the enumerated string and is therefore invalid. MoveNext logically sets the index after the last (nonexistent) character of the enumerated string which is also invalid.

Applies to

Produkt Versioner
.NET Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9
.NET Framework 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard 2.0, 2.1