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fscanf from text file problems

gatinha123 (16)
The error i get is "Exception thrown at 0x0F6CB5F2 (ucrtbased.dll) in Mineseeper.exe: 0xC0000005: Access violation writing location 0xCDCDCDCD" which as far as i could research means i didn't have space to store what I was trying to read, but as far as i can see I've got that covered. Any suggestions?

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typedef struct nodmain  //some blocks with the information i want to save
{
	nod *nextright;
	nodmain *nextdown;
	nodmain *prev;
	int num;
	bool mine;
	bool reveal;
};

typedef struct nod
{
	nodmain *prevmain;
	nod *prevnod;
	nod *nextright;
	int num;
	bool mine;
	bool reveal;
};

//functions to initialize the structs so i can be lazy and just call them :D

nod *Inicializa() //me being lazy
{
	nod *init = (nod*)malloc(sizeof(nod));
	return init;
}

nodmain *Inicializamain() //me being lazy x2
{
	nodmain *init = (nodmain*)malloc(sizeof(nodmain));
	return init;
}


 nodmain *Load(int size)
{
	FILE *Load = fopen("SavedGame.txt", "r");  //the text already exists
	nodmain *auxmain = Inicializamain();
	nodmain *header = auxmain;
	char boolstringmine[10];
	char boolstringreveal[10];
	
	for (int i = 0; i < size; i++)
	{
		fscanf(Load, "%d,%s,%s\t", auxmain->num, &boolstringmine, &boolstringreveal);  //ERROR here
		if (boolstringmine == "true")
		{
			auxmain->mine = true;
		}
		else
		{
			auxmain->mine = false;
		}
		if (boolstringreveal == "true")
		{
			auxmain->reveal = true;
		}
		else
		{
			auxmain->reveal = false;
		}
		nod *aux = Inicializa();
		auxmain->nextright = aux;
		aux->prevmain = auxmain;
		aux->prevnod = NULL;
		for (int j = 0; j < (size - 2); j++)
		{
			fscanf(Load, "%d,%s,%s\t", aux->num, &boolstringmine, &boolstringreveal);
			if (boolstringmine == "true")
			{
				aux->mine = true;
			}
			else
			{
				aux->mine = false;
			}
			if (boolstringreveal == "true")
			{
				aux->reveal = true;
			}
			else
			{
				aux->reveal = false;
			}
			nod *nextnod = Inicializa();
			nextnod->prevnod = aux;
			nextnod->prevmain = NULL;
			aux->nextright = aux;
			aux = aux->nextright;
		}
		nodmain *nextmain = Inicializamain();
		auxmain->nextdown = nextmain;
		nextmain->prev = auxmain;
		auxmain = nextmain;
		fscanf(Load, "\n");
	}
	
	fclose(Load);

	return header;
}

//this function is the one that writes on the text file, works perfectly.
void Save(nodmain *header)
{
	FILE *Save = fopen("SavedGame.txt", "w");
	nodmain *auxmain = header;
	nod *aux = Inicializa();

	if (Save == NULL)
	{
		printf("ERROR");
	}
	else
	{
		while (auxmain != NULL)
		{
			fprintf(Save, "%d,%s,%s\t", auxmain->num, auxmain->mine ? "true" : "false", auxmain->reveal ? "true" : "false");
			aux = auxmain->nextright;
			while (aux != NULL)
			{
				fprintf(Save, "%d,%s,%s\t", aux->num, aux->mine ? "true" : "false", aux->reveal ? "true" : "false");
				aux = aux->nextright;
			}
			fprintf(Save, "\n");
			auxmain = auxmain->nextdown;
		}
	}
	fclose(Save);
}
Thomas1965 (4571)
fscanf(Load, "%d,%s,%s\t", auxmain->num, &boolstringmine, &boolstringreveal); //ERROR here

fscanf expects a pointer but you pass the address of an pointer &boolstringmine
Try either &boolstringmine[0] OR boolstringmine same for &boolstringreveal
Moschops (7244)
fscanf(Load, "%d,%s,%s\t", auxmain->num, &boolstringmine, &boolstringreveal); //ERROR here

auxmain->num is an int. You're supposed to give the address of that int. You also seem to be giving the address of a pointer to boolstringmine and boolstringreveal, instead of the addresses of those arrays.

If you used C++ instead of C, this would be much easier and much less prone to error.

//functions to initialize the structs so i can be lazy and just call them :D
We have those in C++. They're called constructors. If you're reimplementing, badly, things that C++ comes with, you really should consider moving to C++.


fscanf(Load, "\n");
What's this trying to do?
Last edited on
coder777 (8442)
0xCDCDCDCD is a so called magic number. See:

https://en.wikipedia.org/wiki/Magic_number_(programming)

Used by Microsoft's C/C++ debug malloc() function to mark uninitialized heap memory, usually returned from HeapAlloc()


It actually means there is at least one uninitialized member.
gatinha123 (16)
Changed to :fscanf(Load, "%d,%s,%s\t", &num, boolstringmine, boolstringreveal);
(then aux->num=num and same for auxmain->num)
It now reads from the text file, however the "%s" reads until there's no more space to store, instead of reading till a comma, which is what i'm trying to achieve.

"fscanf(Load, "\n");
What's this trying to do?" -> I put "\n" to change lines in the save function (easier to confirm the information on the text file), so i have to let the reader function know its supposed to change lines, am i wrong?







Thomas1965 (4571)
gatinha123 (16)
Thank you that solved the comma problem ^~^
However something else came up...
When scanning the string until commas it scans something like "true\0?????", but if i compare string=="true" it returns false? Sorry if I'm having way too many doubts I'm new to programming >.<
Thomas1965 (4571)
You can't compare them with ==, this works only for C++ strings. You need to use strcmp
http://www.cplusplus.com/reference/cstring/strcmp/
gatinha123 (16)
Thank you everything seems to be working perfectly know ^~^
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