Why is my Condition Structure assigning a value to a variable?

Question

My code below represents the scenario of keeping a feedback of 5 questions, where:

• Each question is worth 2 points
• Check if 3 students will hit the Feedback
• Calculate Each Student’s Individual Grade
• Calculate the Class Average

My question is right there in the addition of student grades, more specifically in this expression: soma <- soma + 2.

The sum "unites" the values of nota[a], but I did not put the value in the sum to receive the same.

• a) Why this happens?
• b) Because this place uses the + 2?.
• c) The note[a] vector would actually hold a value?

The Place of Doubt:

  nota[a] <- nota[a] + 2
  soma <- soma + nota[a]

My Code:

 Var i,a,c: inteiro    
    resp,gab: vetor[1..5] de caractere   
    nome: vetor[1..3] de caractere
    nota: vetor[1..5] de real
    m,soma: real

    Inicio

    Para i <- 1 ate 5 faca
            Escreva("Digite o gabarito ", i)
            Leia(gab[i]) 
    FimPara
    Para a <- 1 ate 3 faca
            EscrevaL("ALUNOS ", a)
            Escreva("Nome: ")
            Leia(nome[a])
            Para c <- 1 ate 5 faca
                 Escreva("Digite a questão ", c)
                 Leia(resp[c])
                 Se (gab[i]=resp[c]) entao
                    EscrevaL(" acertou a ", c)
                    nota[a] <- nota[a] + 2
                    soma <- soma + 2
                 FimSe
            FimPara
            m <- soma/3
    FimPara 
    Para a <- 1 ate 3 faca
            EscrevaL(nome[a]: 10, nota[a])
    FimPara
    Escreva("Média da Turma: ", m)

Answer 1

Note that here:

 Se (gab[i]=resp[c]) entao

variable i has the value it had at the end of the feedback loop. I think it should be:

 Se (gab[c]=resp[c]) entao

You need to assign an incial value to each position of the note vector, for example nota[a] <- 0 right after reading the name.

You recalculate the average for each student and don’t calculate the class average, just print the calculation of the last student.

Var
    i,a,c: inteiro    
    resp,gab: vetor[1..5] de caractere   
    nome: vetor[1..3] de caractere
    nota: vetor[1..3] de real
    m,soma: real
Inicio
    Para i <- 1 ate 5 faca
        Escreva("Digite o gabarito ", i)
        Leia(gab[i]) 
    FimPara
    soma <- 0
    Para a <- 1 ate 3 faca
        EscrevaL("ALUNOS ", a)
        Escreva("Nome: ")
        Leia(nome[a])
        nota[a] <- 0
        Para c <- 1 ate 5 faca
            Escreva("Digite a questão ", c)
            Leia(resp[c])
            Se (gab[c]=resp[c]) entao
                EscrevaL(" acertou a ", c)
                nota[a] <- nota[a] + 2
                soma <- soma + 2
            FimSe
        FimPara
    FimPara 
    Para a <- 1 ate 3 faca
             EscrevaL(nome[a]: 10, nota[a])
    FimPara
    m <- soma/3
    Escreva("Média da Turma: ", m)
fimalgoritmo

Answer 2

welcome (to).

At first, to fix your code you need to change this line:

Se (gab[i]=resp[c]) entao

To:

Se (gab[c]=resp[c]) entao //mudei o 'i' pelo 'c'

Because in the first way, i was not updated, and so you always compared the answer with a value of the template.

On the question of note[a], I did not understand what you meant by

"The "sum" joins the values of every note[a] but I did not put value in it for her to receive nothing. Why does this happen?".

About why to use +2 instead of note[a] in the sum. It turns out, the way the code is, every time you put the first student’s answer to a question, it updates the value of note[a] and sum with the same value. Thus, when answering the 5 questions to the first student, the grade value[1°student] will be equal to the sum of.

When going to the second student, note[2°student] starts at zero, while sum already has the value of the score of the first student, so if you do 'sum <- sum + note[a]' when the second student hits the first question, will be added zero to the sum variable (sum <- sum + note[a], note[a] being zero).

An alternative to using 'sum <- sum + note[a]' would be to do the code as below:

    Var

i,a,c: inteiro
resp,gab: vetor[1..5] de caractere
nome: vetor[1..3] de caractere
nota: vetor[1..5] de real
m,soma: real

Inicio

Para i <- 1 ate 5 faca
        Escreva("Digite o gabarito ", i)
        Leia(gab[i])
FimPara
Para a <- 1 ate 3 faca
        EscrevaL("ALUNOS ", a)
        Escreva("Nome: ")
        Leia(nome[a])
        Para c <- 1 ate 5 faca
             Escreva("Digite a questão ", c)
             Leia(resp[c])
             Se (gab[c]=resp[c]) entao
                EscrevaL(" acertou a ", c)
                nota[a] <- nota[a] + 2

             FimSe
        FimPara
        soma <- soma + nota[a] //essa instrução está fora do 'para' que itera 'a'
FimPara
m <- soma/3 //essa linha pode ficar fora dos dois 'para'
Para a <- 1 ate 3 faca
        EscrevaL(nome[a]: 10, nota[a])
FimPara
Escreva("Média da Turma: ", m)


Fimalgoritmo

I’m not sure if I was clear, or if I answered (right) all your questions, anything, edit your question to address the other question points.

Answer 3

The "sum" adds the values of note[a] but I did not put value in "sum" for her to receive. Why does this happen?

This happens, because you put the operation + 2 in the same line, as you did not start the sum variable it is worth 0, but in the same line you assign 2 the variable, see below:

soma <- soma + 2.

It would be exactly the same as:

soma = 0 + 2

And one more question, why there is + 2 ?

Because you have 5 questions and the maximum score is 10, so if you had 10 questions the increment would be +1

Why couldn’t it be that way?

nota[a] <- nota[a] + 2

soma <- soma + nota[a]

You’re right the best way to do it is like this!

Then the note[a] goes to "sum" and it would actually keep a value ?

Again it is correct, it would save the value, and you will need both variables soma and nota[a], because they are used in different steps of your code.

I made some corrections to your code:

Inicio
// Seção de Comandos, procedimento, funções, operadores, etc... 
 Para i <- 1 ate 5 faca
        Escreva("Digite o gabarito ", i)
        Leia(gab[i])
FimPara
Para a <- 1 ate 3 faca
        EscrevaL("ALUNOS ", a)
        Escreva("Nome: ")
        Leia(nome[a])
        Para c <- 1 ate 5 faca
             Escreva("Digite a questão ", c)
             Leia(resp[c])
             Se (gab[c]=resp[c]) entao
                EscrevaL(" acertou a ", c)
                nota[a] <- nota[a] + 2
                soma <- soma + nota[a]
                senão
                 Escreval(" errou a questão: ", c)
                                       // Evite colocar apenas o se.. então, sem um  
                                      //fechamento de senão, pois se não entrar no 
                                     //primeiro laço informará o usuário em qual laço 
                                     //entrou
             FimSe
        FimPara
        m <- soma/3
FimPara
Para a <- 1 ate 3 faca
        EscrevaL(nome[a], " de 10 pontos você tirou: ", nota[a], " pontos")   
                                 //Coloquei mais texto para informar bem o usuário de 
                                 //quanto foi a nota e qual seria a nota máxima
FimPara
Escreva("Média da Turma: ", m)

Fimalgoritmo