Infracción de acceso al llenar la matriz char*

I've written a code in c:

const char *str[125000]; 
float k[125000];
long n;
char string[20];
int i;
scanf("%d",&n);
    for (i=0;i<n;i++)
    {
    scanf("%s%f",&string,&k[i]);
    p=p/k[i];
    str[i]=_strdup(string);
    }

At this point everything's perfect. The array gets filled even if the n=100000; However if I change 

for (i=0;i<n;i++)

a 

for (i=n;i>0;i--)

i get the "Access violation" error. I've got no idea why is this happening so I'm asking for your help. Thanks in advance.

preguntado el 09 de septiembre de 13 a las 21:09

This is like one line different than your last question: stackoverflow.com/questions/18676383/… -

2 Respuestas

Arrays in C the size of n go from 0 to n - 1. So your loop should be 

for (i=n-1;i>=0;i--)

You get an error because you are trying to access memory out of bounds of that array.

Respondido el 09 de Septiembre de 13 a las 21:09

Wow, it did work. Thanks a lot. But I still don't get it. Even if the loop goes from n to 1, why would that matter, considering that the array's size is 125000 and n<=100000? - DannyPhantom

@DannyPhantom I don't know what was your test code, show the sscce. - este

1 vsync 10 that's the simplest test code which was failing. - DannyPhantom

No se que es eso 1 vsync 10 medio. - este

@DannyPhantom I just noticed that const char *str[125000]; y scanf("%s%f",&string no funcionará. - este

When reading a character string using %s you should not pass the address of the string, instead simply pass the string: scanf("%s%f",string,&k[i]);.

Respondido el 09 de Septiembre de 13 a las 21:09

@Chad I am not sure I understand your comment but the way OP reads the value of k[i] seems ok to me. - Ivailo Strandjev

@DannyPhantom this is only one of your errors it seems. Also take a look at this.'s answer - Ivailo Strandjev

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