当我输入vaue &records[*rCount].source时，.source会崩溃

Question

最新情况*

我现在已经尝试从函数中返回一些东西，但仍然是.exe崩溃！我对c很陌生，很抱歉，如果我有点笨，不知道为什么。

struct packet* addRecord(int *rCount, struct packet *records){
int valid = 0;  //used to indicated valid input
int length = 0; //used to store the string lengths
int i = 0;    //used in the for loops
char dataTest[51];     //temporary storage of input to be checked before adding to records




do{
    puts("What is the source of this packet?: ");
    if(scanf(" %c", &records[*rCount].source) == 1){  //if correct insert the record at the index
        valid=1;                                //determined by rCount(the current record count passed to addRecord
    }
    else{
        valid = 0;
        getchar();
        puts("\nNot a valid input");
    }

}while(valid!=1);

do{
    puts("What is the destination of this packet?: ");
    if(scanf(" %c", &records[*rCount].destination) == 1)
    {
        valid = 1;
    }
    else
    {
        valid = 1;
        getchar();
        puts("\nNot a valid input");
    }
   }
   while(valid!=1);
   records = realloc(records,(*rCount+1)*sizeof(struct packet));
   return records;

}

因此，这段代码可以工作，但是当我为&records*rCount.source输入一个值时，.exe就会崩溃。我已经看了这段代码一个小时了，找不到断了的链接，但我觉得它很简单。

下面是一些我觉得工作不正常的代码。

另外，请有人解释一下== 1在if语句中的含义，我刚刚把这段代码合并在一起。谢谢

do{
        puts("What is the source of this packet?: ");
        if(scanf("%i", &records[*rCount].source) == 1){  //if correct insert the record at the index
            valid=1;                                //determined by rCount(the current record count passed to addRecord
        }
        else{
            valid = 0;
            getchar();
            puts("\nNot a valid input");
        }

    }while(valid!=1);

完整代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

struct packet{ // declare structure for packet creation
        int source;
        int destination;
        int type;
        int port;
        char data[51];
    };

//function prototypes
void listRecords(int, struct packet*);
struct packet* addRecord(int*, struct packet*);
void save(int, struct packet*);
struct packet* open(int*, struct packet*);

int main ()
{
    int recordCount = 0;
    char choice;
    struct packet *records;
    struct packet *temp;

    do {
                printf("\nWhat would you like to do?\n");

                printf("\t1) Add a packet.\n");                 //---------------------//
                printf("\t2) List all packets.\n");             //---------------------//
                printf("\t3) Save packets.\n");                 //---------MENU--------//
                printf("\t4) Clear all packets.\n");            //---------------------//
                printf("\t5) Quit the programme.\n");           //---------------------//

                scanf("%i", &choice); // scan user input and put the entry into variable "choice"
                if(choice == '/n')
                    scanf("%i", &choice);



                switch(choice)
                {
                    case 1: system("cls");
                            records = addRecord(&recordCount, records);
                            break;
                    case 2: system("cls");
                            break;
                    case 3: system("cls");
                            break;
                    case 4: system("cls");
                            break;
                    default: system("cls");
                             printf("%i was not a valid option\n", choice);
                             break;
                }

            }
    while (choice != 5);
    return 0;
}

struct packet* addRecord(int *rCount, struct packet *records){
    int valid = 0;  //used to indicated valid input
    int length = 0; //used to store the string lengths
    int i = 0;    //used in the for loops
    char dataTest[51];     //temporary storage of input to be checked before adding to records




    do{
        puts("What is the source of this packet?: ");
        if(scanf("%i", &records[*rCount].source) == 1){  //if correct insert the record at the index
            valid=1;                                //determined by rCount(the current record count passed to addRecord
        }
        else{
            valid = 0;
            getchar();
            puts("\nNot a valid input");
        }

    }while(valid!=1);

    do{
        puts("What is the destination of this packet?: ");
        if(scanf("%i", &records[*rCount].destination == 1))
        {
            valid = 1;
        }
        else
        {
            valid = 1;
            getchar();
            puts("\nNot a valid input");
        }
       }
       while(valid!=1);
}

Answer 1

结构化数据包*记录；

这一切都很好，但实际上您从未为这个指针创建一个指向的struct packet。因此，通过该指针进行的所有访问都指向不属于您的无效内存。

我不认为这里需要指针。只需声明如下：

struct packet records;

然后传递指向该对象的指针：

case 1: system("cls");
    addRecord(&recordCount, &records);

注意，我已经去掉了addRecord的返回；您根本不需要它。让它返回void。就像现在一样，您正在接受一个无效指针，并用另一个填充了随机性的无效指针覆盖它，因为您从来没有实际地return任何东西。这是同样的问题，只是碰巧触发了崩溃，因为你得到的随机值。

Answer 2

变化

 if(scanf("%i", &records[*rCount].destination == 1))

至

 if(scanf("%d", &records[*rCount].destination) == 1)  

另外，将%i更改为%d，将char choice;更改为int choice;，另一个问题是您的函数没有返回任何内容，该函数具有指向struct packet返回类型的指针。

在进行了一些更改之后，编译代码如下：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

struct packet{ // declare structure for packet creation
        int source;
        int destination;
        int type;
        int port;
        char data[51];
    };

//function prototypes
void listRecords(int, struct packet*);
void addRecord(int*, struct packet*);
void save(int, struct packet*);
struct packet* open(int*, struct packet*);

int main (void)
{
    int recordCount = 0;
    int choice;
    struct packet *records;
    //struct packet *temp;

    do {
                printf("\nWhat would you like to do?\n");

                printf("\t1) Add a packet.\n");                 //---------------------//
                printf("\t2) List all packets.\n");             //---------------------//
                printf("\t3) Save packets.\n");                 //---------MENU--------//
                printf("\t4) Clear all packets.\n");            //---------------------//
                printf("\t5) Quit the programme.\n");           //---------------------//

                scanf("%d", &choice); // scan user input and put the entry into variable "choice"
                if(choice == '\n')
                    scanf("%d", &choice);



                switch(choice)
                {
                    case 1: system("cls");
                             addRecord(&recordCount, records);
                             break;
                    case 2: system("cls");
                             break;
                    case 3: system("cls");
                             break;
                    case 4: system("cls");
                             break;
                    default: system("cls");
                             printf("%d was not a valid option\n", choice);
                             break;
                }

            }
    while (choice != 5);
    return 0;
}

void addRecord(int *rCount, struct packet *records){
    int valid = 0;  //used to indicated valid input
    //int length = 0; //used to store the string lengths
    //int i = 0;    //used in the for loops
    //char dataTest[51];     //temporary storage of input to be checked before adding to records




    do{
        puts("What is the source of this packet?: ");
        if(scanf("%d", &records[*rCount].source) == 1){  //if correct insert the record at the index
            valid=1;                                //determined by rCount(the current     record count passed to addRecord
        }
        else{
            valid = 0;
            getchar();
            puts("\nNot a valid input");
        }

    }while(valid!=1);

    do{
        puts("What is the destination of this packet?: ");
        if(scanf("%d", &records[*rCount].destination) == 1)
        {
            valid = 1;
        }
        else
        {
            valid = 1;
            getchar();
            puts("\nNot a valid input");
        }
    }
       while(valid!=1);
}

Answer 3

%i应该做什么？你在找整数吗？如果是这样，则需要%d (d表示小数)。

== 1检查是否已成功地处理了1项。

和@haccks所说的失踪)。