当我为 records[*Count].source 输入一个值时，.exe 崩溃

Question

更新*

我现在尝试从函数中返回一些东西，但 .exe 仍然崩溃！我对 c 很陌生，如果我有点粗心没有发现原因，我很抱歉。

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;

}

所以我已经让这段代码工作了，但是当我为 &records[*rCount].source 输入一个值时，.exe 崩溃了。我一直在看这段代码一个小时，找不到损坏的链接，但我觉得它很简单。

这是我觉得不能正常工作的一小段代码。

也有人可以解释一下 if 语句中 == 1 的含义，我只是将这段代码一起破解了。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

改变

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

到

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

还将%i 更改为%d 和char choice; 更改为int choice; 另一个问题是你没有从你的函数中返回任何东西，它有指向 struct packet 返回类型的指针。

我做了一些修改后的编译代码是：

#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 2

struct packet *records;

一切都很好，但您实际上从未为此指针创建一个 struct packet 指向。因此，通过这个指针的所有访问都是对不属于你的无效内存。

我认为这里不需要指针。简单地声明为：

struct packet records;

然后传递一个指向该对象的指针：

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

请注意，我已经取消了 addRecord 的返回；你根本不需要它。让它返回void。就像现在一样，您正在使用一个无效指针并用 another 填充了随机性的无效指针覆盖它，因为您从来没有实际上 return 任何东西。也是同样的问题，只是碰巧因为你得到的随机值触发了崩溃。

Answer 3

%i 应该做什么？你在找一个整数吗？如果是这样，您需要 %d（d 表示十进制）。

== 1 检查 scanf 是否成功处理了 1 个项目。

以及@hacks 所说的丢失）。