Help with While in c++

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I was curious about the following code in c++.

int main(int argc, char** argv) {
    float n1,n2,n3,n4;
    int i = 1;
    char nomeAluno;
    
    printf("Digite seu nome: ");
    scanf("%s", &nomeAluno);
    while(i<5){
        printf("Digite sua %dº nota: ", i);
        scanf("%f", &n1);
        
        i++;
    }
    printf("%.1f \n", n1);
    printf("%.1f \n", n2);
    printf("%.1f \n", n3);
    printf("%.1f \n", n4);
    return 0;
}

I have the following doubt, I don’t know if it’s possible, but if it’s how I can get inside the while the next note typing falls inside the N2? Because this way I did it keeps storing only in n1(Of course because of the loop).

c++ while
  • 2

    The statement char nomeAluno; defines the variable that will contain one single character (in this case the format is %c) and not a string. For a string, which in C is an array of characters with the terminator character ' 0', use char nomeAluno[40]; and in the scanf function do not put &. In fact in C++ you should use the string class. As for the notes you put the reading inside a loop and therefore every new reading you overwrite what was read in the previous reading. Either take separate readings for each note or use an array of notes (float nota[4];).

  • I didn’t notice the difference between using %c and %s over & didn’t know it was better to use a string. I’ll study more anyway and I’m grateful for the advice. :)

1 answer

3

You can use vectors. To declare them, it is simple, just type the variable and then between keys [] the number of positions that will receive the variable float n[4], here I declared a float type array of 4 positions (remembering that C++ the values of a vector start with 0).

A practical example of what your code would look like:

int i = 0;
float n[4];
while(i<4){
    printf("Digite sua %dº nota: ", i+1);
    scanf("%f", &n[i]);
    
    i++;
}
printf("%.1f \n", n[0]);
printf("%.1f \n", n[1]);
printf("%.1f \n", n[2]);
printf("%.1f \n", n[3]);
return 0;
}

Note that I declare int i = 0, and that in the printf, I add i + 1 to print in the way that has to be shown to the user, this value will change only in printing, and will not add in variable i.

To see more about, I recommend these two links:

http://linguagemc.com.br/vetores-ou-arrays-em-linguagem-c/

https://www.inf.pucrs.br/~pinho/Laproi/Vectors/Vectors.htm

  • Thank you, I will use vectors then. And thank you for the links. D

  • You’re welcome, my friend, you had an errata, in while() i put while(i<5), actually is while(i<4) and read enquanto i for menor que 4, because we only have four positions to fill, and the variable i begins with 0, now that’s correct. Remembering that it is dangerous in a program to give values to a vector larger than itself, you are changing the memory that may be being used by another instance, variable, etc.

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