Segmentation fault (core dumped)

**catasturslykid** · 07-29-2013

Hi again, guys!

There's a problem with my code and I can't find it... Can u help me?

Code:

 

void carregaClasses(FILE *g, Classe *classe, int *nClas){

int nAtac, nDefensa, nVida, i;
char strNom[100], kk;

fscanf(g,"%d", &nClas);
fscanf(g,"%c", &kk);

classe = (Classe*)malloc(sizeof(Classe) * *nClas);
if(classe == NULL){
    printf("Error!\n");
}
else{
    for(i = 0; i < *nClas; i++){
        fscanf(g,"%s", strNom);
        fscanf(g,"%c",&kk);
        fscanf(g,"%d", &nAtac);
        fscanf(g,"%c", &kk);
        fscanf(g,"%d", &nDefensa);
        fscanf(g,"%c", &kk);
        fscanf(g,"%d",&nVida);
        
        strcopy(strNom, classe[i].strNom);
        classe[i].nAtac = nAtac;
        classe[i].nDefensa = nDefensa;
        classe[i].nVida = nVida;
        fscanf(g,"%c",&kk);  
    }
 }
}

While executing the code, the error SEGMENTATION FAULT appears... why? Where?

Thank you!

**grumpy** · 07-29-2013

nClass is a pointer to int. The first fscanf() treats that pointer as if it is an int. That is undefined behaviour. In short, remove the ampersand.

And that's assuming the code which calls the function does what is expected and sane. If the caller does not do what is expected and sane, all bets are even more off.

Even worse, the change of classe inside your function is not visible to the caller. That will cause a memory leak at best. It will certainly cause a problem if the caller expects the pointer it passes to be allocated - because it won't be.

There is also no such function as strcopy(), so your code as listed should not even compile.

Don't even get me started on the fact your code doesn't check that the fscanf() calls succeed.

**catasturslykid** · 07-29-2013

Originally Posted by grumpy

nClass is a pointer to int. The first fscanf() treats that pointer as if it is an int. That is undefined behaviour. In short, remove the ampersand.

And that's assuming the code which calls the function does what is expected and sane. If the caller does not do what is expected and sane, all bets are even more off.

Even worse, the change of classe inside your function is not visible to the caller. That will cause a memory leak at best. It will certainly cause a problem if the caller expects the pointer it passes to be allocated - because it won't be.

There is also no such function as strcopy(), so your code as listed should not even compile.

Don't even get me started on the fact your code doesn't check that the fscanf() calls succeed.

Yeah, that was the problem! Thank you for your complete and fast answer, grumpy! Really appreciate it!

Another question to you: What do you mean with "There is also no such function as strcopy(), so your code as listed should not even compile."?

**grumpy** · 07-29-2013

Originally Posted by catasturslykid

What do you mean with "There is also no such function as strcopy(), so your code as listed should not even compile."?

What is ambiguous about that statement? There is no function in the standard C library named strcopy().

**catasturslykid** · 07-29-2013

Originally Posted by grumpy

What is ambiguous about that statement? There is no function in the standard C library named strcopy().

Oh, that's true! haha I typed strcopy() while it's strcpy()! Thank you again!

Thread: Segmentation fault (core dumped)

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