With what function do I find the position of a letter within a string?

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With what function do I find the position of a letter within a string?

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#1 by (0 votes)

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I want to know in what position the letter "x" is located within the variable "equation"

public static void main(String[] args) 
    {
        /*
        Resolver una ecuacion de primer grado con 1 variable 
        ejemplo:
        2x-1=5x+8
        */
        Scanner into=new Scanner(System.in);
        System.out.println("Ingrese una escuacion de primer grado: ");
        String ecuacion=into.next();
        int caracteres=ecuacion.length();
        int num=caracteres;
        System.out.println(num);
        String[] caracter=new String[num];
        int paso=0;
        int pasa=1;
        for(int a=0;a<=num;a++)
        {
            //separador de letras
            caracter[a]=ecuacion.substring(paso,pasa);
            System.out.println(caracter[a]);
            paso++;
            pasa++;
        }
    for(int b=0;b<=num;b++)
    {

    }

}

java string

asked by DeTrolean 05.07.2018 в 04:13

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1 answer

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score 0 · Accepted Answer

With the use of indexOf you can achieve what you need.

You can do it in the following way to find only the first occurrence or all the occurrences in case you need it later:

public static void main(String[] args) {
        String ecuacion = "3x+1=3-2(2-2x)";
        String letra = "x";

        // Primera ocurrencia
        System.out.println("Primera ocurrencia...\nPosición: " + ecuacion.indexOf(letra)); // Imprime: 1

        // Encontrar todas las ocurrencias
        System.out.println("\nTodas las ocurrencias...");
        for (int i = -1; (i = ecuacion.indexOf(letra, i + 1)) != -1; i++) {
            System.out.println("Posición: " + i);
        } // Imprime: 1 y 12
    }

Result:

Primera ocurrencia...
Posición: 1

Todas las ocurrencias...
Posición: 1
Posición: 12