fprintf output is returning unpredictable results - c

Question

My fprintf() is returning unpredictable results. I think it is returning the memory address number instead of the data inside the memory address. Can someone have a look at my code and check it out? When I used the &source within the fprintf() I'm told it is undeclared and when I declare it in the top of the function it doesn't work.
#include <stdio.h>
#include <stdlib.h>
int MenuLoop = 0;
int MaxPackets = 4;
int currentPackets= 0;
int menu;
/*********************************************************
* Node to represent a Cat which includes a link reference*
* a link list of nodes with a pointer to a Cat Struct *
* would be better but this is for illustartion only! *
**********************************************************/
struct Packet {
int Source;
int Destination;
int Type;
int Port;
char *Data;
struct Packet *next; // Link to next Cat
};
typedef struct Packet node; // Removes the need to constantly refer to struct
/*********************************************************
* Stubs to fully declared functions below *
**********************************************************/
void outputPackets(node **head);
void push(node **head, node **aPacket);
node* pop(node **head);
void AddPacket();
void AddPacket();
void SavePacket();
void ShowCurrent();
void ExitProgramme();
main() {
do{
Menu();
} while(menu<4);
}
void AddPacket(){
int option;
/*********************************************************
* pointers for the link list and the temporary P to *
* insert into the list *
**********************************************************/
node *pPacket, *pHead = NULL;
/*********************************************************
* Create a cat and also check the HEAP had room for it *
**********************************************************/
pPacket = (node *)malloc(sizeof(node));
if (pPacket == NULL)
{
printf("Error: Out of Memory\n");
exit(1);
}
currentPackets++;
printf("Enter Source Number between 1-1024:\n");
scanf("%i", &pPacket->Source);
printf("Enter Destination Number between 1-1024:\n");
scanf("%i", &pPacket->Destination);
printf("Enter Type Number between 0-10:\n");
scanf("%i", &pPacket->Type);
printf("Enter Port Number between 1-1024:\n");
scanf("%i", &pPacket->Port);
printf("Enter Data Numberbetween 1-50:\n");
scanf("%s", &pPacket->Data);
printf("Do you want to Enter another Packet?");
pPacket->next = NULL;
/*********************************************************
* Push the Cat onto the selected Link List, the function *
* is written so the program will support multiple link *
* list if additional 'pHead' pointers are created. *
* Who says you cannot herd cats! *
**********************************************************
* NOTE: The push parameters are using references to the *
* pointers to get round the pass by value problem caused *
* by the way C handles parameters that need to be *
* modified *
**********************************************************/
push(&pHead, &pPacket);
pPacket = (node *)malloc(sizeof(node));
if (pPacket == NULL)
{
printf("Error: Out of Memory\n");
exit(1);
}
outputPackets(&pHead);
/*********************************************************
* Display the Link List 'pHead' is passed as a reference *
**********************************************************/
return 0;
do{
if(currentPackets == MaxPackets);
{
printf("Packet limit reached please save\n");
}
}while(currentPackets<MaxPackets);
return 0;
}
void outputPackets(node **head)
{
/*********************************************************
* Copy Node pointer so as not to overwrite the pHead *
* pointer *
**********************************************************/
node *pos = *head;
/*********************************************************
* Walk the list by following the next pointer *
**********************************************************/
while(pos != NULL) {
printf("Source: %.4i Destination: %.4i Type: %.4i Port: %.4i \n", pos->Source, pos->Destination, pos->Type, pos->Port);
pos = pos->next ;
}
printf("End of List\n\n");
}
void push(node **head, node **aPacket)
{
/*********************************************************
* Add the cat to the head of the list (*aCat) allows the *
* dereferencing of the pointer to a pointer *
**********************************************************/
(*aPacket)->next = *head;
*head = *aPacket;
}
node *pop(node **head)
{
/*********************************************************
* Walk the link list to the last item keeping track of *
* the previous. when you get to the end move the end *
* and spit out the last Cat in the list *
**********************************************************/
node *curr = *head;
node *pos = NULL;
if (curr == NULL)
{
return NULL;
} else {
while (curr->next != NULL)
{
pos = curr;
curr = curr->next;
}
if (pos != NULL) // If there are more cats move the reference
{
pos->next = NULL;
} else { // No Cats left then set the header to NULL (Empty list)
*head = NULL;
}
}
return curr;
}
void SavePacket(Source, Destination, Type, Port, Data){
FILE *inFile ;
char inFileName[10] = { '\0' } ;
printf("Input file name : ") ;
scanf("%s", inFileName) ;
//Open file
inFile = fopen(inFileName, "w+");
if (!inFile)
{
fprintf(stderr, "Unable to open file %s", &inFile);
exit(0);
}
fprintf(inFile, "Source: %i Destination: %i Type: %i Port: %i Data: %s \n", Source, Destination, Type, Port, Data);
fclose(inFile);
}
void ShowCurrent(){
}
void ExitProgramme(){}
void Menu(){
printf("********Welcome****** \n");
printf("Creator Ben Armstrong.\n\n");
printf("*Please Choose an option*\n");
printf("1. Add a new packet\n");
printf("2. Save current packet to file\n");
printf("3. Show current list of packets\n");
printf("4. Exit\n");
scanf("%i", &menu);
switch(menu)
{
case 1:
AddPacket();
break;
case 2:
SavePacket();
break;
case 3 :
ShowCurrent();
break;
case 4 :
ExitProgramme();
break;
}
}

Answer 1

Here's part of your problem...
inFile = fopen(inFileName, "w+");
if (!inFile)
{
fprintf(stderr, "Unable to open file %s", &inFile);
exit(0);
}
I'm pretty sure you mean...
inFile = fopen(inFileName, "w+");
if (!inFile)
{
fprintf(stderr, "Unable to open file %s", inFileName );
exit(0);
}
Also note that &inFile is the address of the inFile variable, not the value stored in the FILE pointer.
Additionally, you declare your function prototype for saving the data as follows...
void SavePacket(Source, Destination, Type, Port, Data)
which says you're passing in a Source, a Destination, a Type, a Port and a Data argument, but apparently you mean those to be the names, not the types, so the compiler is assuming they are all integers. You need to give them a type and a name...
void SavePacket( int Source, int Destination, int Type, int Port, char* Data)
and now you can print them...
fprintf(
inFile, "Source: %i Destination: %i Type: %i Port: %i Data: %s \n",
Source, Destination, Type, Port, Data
);
But you have a much bigger mess going on, as you're declaring that SavePacket() should receive arguments, but you don't pass arguments to it when you call it...
case 2:
SavePacket();
break;
Which should be passing in the variables you need to print. Something like...
case 2:
SavePacket(
somePacket->Source, somePacket->Destination, somePacket->Type,
somePacket->Port, somePacket->Data
);
break;
But, you could make that easier this way...
void SavePacket( struct Packet* packet )
{
...
fprintf(
inFile, "Source: %i Destination: %i Type: %i Port: %i Data: %s \n",
packet->Source, packet->Destination, packet->Type,
packet->Port, packet->Data
);
}
And then call it by passing in the packet...
case 2:
{
struct Packet somePacket;
GetPacketDataFromSomewhere( &somePacket );
SavePacket( &somePacket );
break;
}