C# Program to Find the Last Occurrence Character In a String

In this post, we'll discuss two different ways to find the last occurrence of a character in a string using C#.

1) Using LastIndexOf() Method

The easiest method to find the last occurrence of a character in a string is using the LastIndexOf() method.

string data = "Hello World";
int lastIndex = data.LastIndexOf('o');
Console.WriteLine("The last index is: " + lastIndex);

If you want to perform a case-insensitive comparison, use this code instead.

string data = "Hello World";
int lastIndex = data.LastIndexOf("o", StringComparison.OrdinalIgnoreCase);
Console.WriteLine("The last index is: " + lastIndex);

2) Manually Finding the Last Occurrence

This is how we can manually find the last occurrence of a character.

string data = "Hello World";
char charToSearch = 'o';
int lastIndex = 0;

for (int i = 0; i < data.Length; i++)
{
    if (data[i] == charToSearch)
    {
        lastIndex = i;
    }
}

Console.WriteLine("The last index is: " + lastIndex);

For case-insensitive search:

string data = "Hello World";
char charToSearch = 'o';
int lastIndex = 0;

//charToSearch = char.ToLower(charToSearch);
for (int i = 0; i < data.Length; i++)
{
    char chr = char.ToLower(data[i]);
    if (chr == charToSearch)
    {
        lastIndex = i;
    }
}

Console.WriteLine("The last index is: " + lastIndex);

Happy coding 👍.