How to store letters in a variable and display them all at the end by forming a phrase/word

Question

I’m holding up programming and I’m making a code where I’m supposed to turn a binary code into a phrase. I’m turning the binary value into decimal, and taking the decimal value and comparing the ASCII table. However, I don’t know how to keep the letters that appear in a variable or vector to display them all together at the end.

int main()
{
    setlocale(LC_ALL, "Portuguese");

    int dec=0,num,d=1;
    char charr[25];

    cout<<" Digite o numero binario de 8 dígitos (dígite 0 para parar): ";
    cin>>num;

    do {
    dec = dec+(num%10)*d;
    d = d*2;
    num = num/10;
    }

    while(num!=0);

    charr[0] = 'A', charr[16] = 'Q';
    charr[1] = 'B', charr[17] = 'R';
    charr[2] = 'C', charr[18] = 'S';
    charr[3] = 'D', charr[19] = 'T';
    charr[4] = 'E', charr[20] = 'U';
    charr[5] = 'F', charr[21] = 'V';
    charr[6] = 'G', charr[22] = 'W';
    charr[7] = 'H', charr[23] = 'X';
    charr[8] = 'I', charr[24] = 'Y';
    charr[9] = 'J', charr[25] = 'Z';
    charr[10] = 'K';
    charr[11] = 'L';
    charr[12] = 'M';
    charr[13] = 'N';
    charr[14] = 'O';
    charr[15] = 'P';

    if (dec == 65 or dec == 97)
    {
        cout<<charr[0];
    }

    if (dec == 66 or dec == 98)
    {
        cout<<charr[1];
    }

        if (dec == 67 or dec == 99)
    {
        cout<<charr[2];
    }

        if (dec == 68 or dec == 100)
    {
        cout<<charr[3];
    }

        if (dec == 69 or dec == 101)
    {
        cout<<charr[4];
    }

        if (dec == 70 or dec == 102)
    {
        cout<<charr[5];
    }

        if (dec == 71 or dec == 103)
    {
        cout<<charr[6];
    }

        if (dec == 72 or dec == 104)
    {
        cout<<charr[7];
    }


        if (dec == 73 or dec == 105)
    {
        cout<<charr[8];
    }

        if (dec == 74 or dec == 106)
    {
        cout<<charr[9];
    }

        if (dec == 75 or dec == 107)
    {
        cout<<charr[10];
    }

        if (dec == 76 or dec == 108)
    {
        cout<<charr[11];
    }

        if (dec == 77 or dec == 109)
    {
        cout<<charr[12];
    }

        if (dec == 78 or dec == 110)
    {
        cout<<charr[13];
    }

        if (dec == 79 or dec == 111)
    {
        cout<<charr[14];
    }

        if (dec == 80 or dec == 112)
    {
        cout<<charr[15];
    }

        if (dec == 81 or dec == 113)
    {
        cout<<charr[16];
    }

        if (dec == 82 or dec == 114)
    {
        cout<<charr[17];
    }

        if (dec == 83 or dec == 115)
    {
        cout<<charr[18];
    }

        if (dec == 84 or dec == 116)
    {
        cout<<charr[19];
    }

        if (dec == 85 or dec == 117)
    {
        cout<<charr[20];
    }

        if (dec == 86 or dec == 118)
    {
        cout<<charr[21];
    }

        if (dec == 87 or dec == 119)
    {
        cout<<charr[22];
    }

        if (dec == 88 or dec == 120)
    {
        cout<<charr[23];
    }

        if (dec == 89 or dec == 121)
    {
        cout<<charr[24];
    }

        if (dec == 90 or dec == 122)
    {
        cout<<charr[25];
    }
    return 0;
}

Answer 1

The first thing is to decide whether to do it in C or C++. It looks like it goes in C++, so use everything in C++ and avoid things in C.

I tried to do here in a better way what I understood is the question. Some things can be done better (can format output a little better, can change the do-while by a for, ask for a text input and not an integer, optimize performance), but I think it is already a great evolution.

#include <iostream>
#include <string>
using namespace std;

int main() {
    string texto = "";
    while (true) {
        int num;
        cout << "Digite o numero binario de 8 dígitos (dígite 0 para parar): ";
        cin >> num;
        cout << endl;
        if (num == 0) break;
        int dec = 0, d = 1;
        do {
            dec += num % 10 * d;
            d *= 2;
            num /= 10;
        } while (num != 0);
        if (!((dec >= 65 && dec <= 90) || (dec >= 97 && dec <= 122))) {
            cout << "Valor digitado está fora da faixa permitida" << endl;
            continue; 
        }
        texto += "ABCDEFGHIJKLMNOPQRSTUVXYZ"[(dec &  ~32) - 65];
    }
    cout << texto;
}

Behold working in the ideone. And in the repl it.. Also put on the Github for future reference.

I took the unnecessary things and started using string in place of a array of char which is a C thing.

I gave an organized, including I left the statements of the variables closer to their use.

I created a loop that is the most important to ask for multiple numbers in sequence. Its output is when typing a number 0.

I created the variable texto that accumulates the letters.

Note that I have extensively used composite data assignment operators, so d *= 2 is the same as d = d * 2. This applies to other variables, including texto which concatenates the letters.

I checked if the number typed is in a valid range of the ASCII table that can be converted.

I killed all the ifs using math. I normalized the number for the letter index. Since what was typed could be uppercase or lowercase I used the operators of & (AND) and ~ (XOR) On top of 32, we ensure that the number is reduced to the range of 65 to 96 (although this is not guaranteed in the code). I also withdrew 65 to reach 0 of the index. The first dec possible equals to the letter A or a. is the initial index of a array or string (that is nothing more than a array of char). With this operation the result will always be 0 to 25, exactly what you wanted (provided that a binary equivalent to valid characters is typed).

I created a text with all letters positioned between 0 until 25 and with the operator [] I took the index calculated in the index according to formula above. The letter found is accumulated in texto.

If you don’t understand any concept you can ask specific new questions for every difficulty you encounter, so it gets more organized.