Variables bursting

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The variables cont_setosa, cont_versicolor, cont_virginica are breaking at the end of the code, why?? How to fix this??

Before Ifs the variables are normal, but after them, there is this change...

#include <stdio.h>
#include <string.h>

typedef struct element{
    int index;
    long double dist;
}Element;

int main(int argc, char const *argv[])
{
    char *classe_aux, classe_main;
    classe_aux = &classe_main;

    int k = 3;
    int i = 0;
    Element el[3] = {{1},
                     {1},
                     {1}};

    int cont_setosa = 0;
    int cont_versicolor = 0;
    int cont_virginica = 0;

    for (i = 0; i < k; i++)
    {
        if (el[i].index == 0)
        {
            cont_setosa++;
        }
        else
        {
            if (el[i].index == 1)
            {
                cont_versicolor++;
            }
            else
            {
                if ( el[i].index == 2)
                {
                    cont_virginica++;
                }
            }
        }
    }

    printf("%i %i %i\n", cont_setosa, cont_versicolor, cont_virginica);

    if ( cont_setosa > cont_versicolor && cont_setosa > cont_virginica)
    {
        strcpy(classe_aux, "Iris-setosa");
    }
    else
    {
        if ( cont_versicolor > cont_setosa && cont_versicolor > cont_virginica)
        {
            strcpy(classe_aux, "Iris-versicolor");
        }
        if ( cont_virginica > cont_setosa && cont_virginica > cont_versicolor)
        {
            strcpy(classe_aux,"Iris-virginica");
        }
    } 

    printf("%i %i %i\n", cont_setosa, cont_versicolor, cont_virginica);
    return 0;
}

Exit:

0 3 0
1936876918 1819239273 29295
c

  • I could not reproduce this situation with your example code, need to make some modification?

  • No, it’s just run normally, there’s no code input, I tested it on two compilers on the computer and one online and it always keeps popping the variables...

1 answer

2


It seems to me that you are corrupting the stack/stack memory.

The variable classe_aux is a pointer that points to classe_main.

classe_main in turn is a variable of type char, it stores only one character, so when you do strcpy(classe_aux, "Iris-setosa") for example, you are allocating the first character 'I' in the classe_main, and the other characters are then allocated in the stack region at positions that other variables are using, corrupting your memory.

If you declare the variable classe_aux as an array of size 16 for example, this would already solve the memory problem in this case.

Link with the code working.

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