Find the position of a letter using FOR

Question

I’m doing a project that is as follows.

The Program asks the user a text and a letter that will be searched within this text and I want it to return me the position.

Ex.: If you put the word "Table" and I want to look for the letter "s" it returns me the answer of "3" which is the position that is the letter "s"

I’m using this code.

string Texto = "", Palavra = "", resposta = "";
int contador = 0;

Texto = txttexto.Text;
Palavra = txtpalavra.Text;

for (int i = 0; i < Texto.Length; i++)
{
    if (Texto.Contains(Palavra))
    {
        contador++;             
    }
}

txtresposta.Text = Convert.ToString(contador);

Answer 1

There are some things wrong there, but I’ll just focus on the crucial error of your task.

This block of code

if (Texto.Contains(Palavra))
{
    contador++;             
}

checks whether the variable Texto contains the variable value Palavra (that should be called letra, right?).

Let’s take a test tabletop (sorry, I couldn’t help).

Each row of the table below represents a loop of repetition

i | Texto | Palavra | Texto.Contains(Palavra) | contador | 
- | ----- | ------- | ----------------------- | -------- |
0 | Mesa  | s       | true                    |    0     |
1 | Mesa  | s       | true                    |    1     |
2 | Mesa  | s       | true                    |    2     |
3 | Mesa  | s       | true                    |    3     |

You understand the problem?

The value of contador will always be the index of the last letter of the word.

---

The first thing you need to keep in mind is that in C#, a string is a string (for simplicity, a array of char). And, like every C#indexed collection, the first item is at position 0. Therefore, from the moment you know the index of a letter, you will need to increment it to 1 to present to the user.

The simplest way to solve this problem is by using the method IndexOf. Something like:

public static void Main()
{
    string texto = "mesa", letra = "s";
    var pos = texto.IndexOf(letra) + 1;
    Console.WriteLine($"Encontrada a letra {letra} na palavra {texto} na posição {pos}");
}

^{See working on . NET Fiddle}

I imagine you’re learning and that’s why you did it using the for, then here a functional code with the same structure as its original code:

public static void Main()
{
    string texto = "mesa"; 
    char letra = 's';

    int i = 0;
    for (i = 0; i < texto.Length; i++)
    {
        if (texto[i] == letra)
            break;            
    }

    Console.WriteLine(Convert.ToString(i + 1));
}

^{See working on . NET Fiddle}