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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;

}


}
4

1 回答 1

2

这是您问题的一部分...

inFile = fopen(inFileName, "w+");

if (!inFile)
{
    fprintf(stderr, "Unable to open file %s", &inFile);
    exit(0);    
}

我很确定你的意思是...

inFile = fopen(inFileName, "w+");

if (!inFile)
{
    fprintf(stderr, "Unable to open file %s", inFileName );
    exit(0);    
}

另请注意,这&inFileinFile变量的地址,而不是存储在 FILE 指针中的值。

此外,您声明用于保存数据的函数原型,如下所示...

void SavePacket(Source, Destination, Type, Port, Data)

这表示您正在传递 a Source, a Destination, a Type, aPort和 aData参数,但显然您的意思是名称,而不是类型,因此编译器假设它们都是整数。你需要给他们一个类型和一个名字......

void SavePacket( int Source, int Destination, int Type, int Port, char* Data)

现在你可以打印它们了...

fprintf(
    inFile, "Source: %i Destination: %i Type: %i Port: %i Data: %s \n", 
    Source, Destination, Type, Port, Data 
);

但是你有一个更大的混乱,因为你声明 SavePacket() 应该接收参数,但是当你调用它时你没有将参数传递给它......

case 2:
    SavePacket();
break;

哪个应该传递您需要打印的变量。就像是...

case 2:
    SavePacket( 
        somePacket->Source, somePacket->Destination, somePacket->Type,
        somePacket->Port, somePacket->Data
    );
    break;

但是,你可以通过这种方式让事情变得更容易......

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 
    );
}

然后通过传入数据包来调用它......

case 2:
{
    struct Packet somePacket;
    GetPacketDataFromSomewhere( &somePacket );
    SavePacket( &somePacket );
    break;
}
于 2013-05-07T18:41:47.383 回答