Question

My task is to initialize a struct in a header with some data. Then using pointers, add/remove data by malloc-ing bigger/smaller chunks and copying the data over.

Currently, my addRecord function doesn't work as it always seems to add the same crap (Part of record number 1):

Name =

Fire Number = attan (Seems to be part of Manhattan)

Street = ork (Seems to be part of New York)

City = cret (Seems to be part of Secret)

State = tan (Seems to be part of Manhattan)

What am I doing wrong?

My header:

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

struct structPointer{
    char name[51];
    char fireNumber[11];
    char street[26];
    char city[26];
    char state[26];
};

My c file:

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include "myData.h"

struct structInit *sP;
struct structInit *sSP;
int recordNumber = 0;
int numberOfAccesses = 0;

int main(void) {
    sP = (struct structInit *) malloc(5 * sizeof(struct structInit));
    sSP = sP;

    memcpy(sP->name,"Adam Baum",51);
    memcpy(sP->fireNumber,"N1234",11);
    memcpy(sP->street,"Top Secret",26);
    memcpy(sP->city,"Manhattan",26);
    memcpy(sP->state,"New York",26);
    sP++;
    recordNumber++;
    memcpy(sP->name,"Adam Zapel",51);
    memcpy(sP->fireNumber,"S4321",11);
    memcpy(sP->street,"Throat",26);
    memcpy(sP->city,"Manhattan",26);
    memcpy(sP->state,"New York",26);
    sP++;
    recordNumber++;
    memcpy(sP->name,"Al Bino",51);
    memcpy(sP->fireNumber,"W1234",11);
    memcpy(sP->street,"White",26);
    memcpy(sP->city,"Anchorage",26);
    memcpy(sP->state,"Alaska",26);
    sP++;
    recordNumber++;
    memcpy(sP->name,"Anne Teak",51);
    memcpy(sP->fireNumber,"E4321",11);
    memcpy(sP->street,"Oak",26);
    memcpy(sP->city,"Woodville",26);
    memcpy(sP->state,"Wisconsin",26);
    sP++;
    recordNumber++;
    memcpy(sP->name,"Barb Dwyer",51);
    memcpy(sP->fireNumber,"N1234",11);
    memcpy(sP->street,"Keepout",26);
    memcpy(sP->city,"Kilgore",26);
    memcpy(sP->state,"Texas",26);
    recordNumber++;
    sP = sSP;

    int sel;
    while (1){
    printf("MENU\n");
    printf("=====\n");
    printf("1. Print All Records\n");
    printf("2. Print Number of Records\n");
    printf("3. Print Size of Database\n");
    printf("4. Add Record\n");
    printf("5. Delete Record\n");
    printf("6. Print Number of Accesses to Database\n");
    printf("7. Exit\n");
    printf("=====\n");
    printf("Enter selection: ");
    scanf("%d", &sel);
    printf("\n");
        switch(sel){
            case 1:
                numberOfAccesses++;
                printAllRecords(sP);
                break;
            case 2:
                numberOfAccesses++;
                fprintf(stderr,"There are a Total of %d records.\n\n", recordNumber);
                break;
            case 3:
                numberOfAccesses++;
                printSizeOfDatabase(sP);
                break;
            case 4:
                numberOfAccesses++;
                sP = sSP;
                addRecord(sP);
                break;
            case 5:
                numberOfAccesses++;
                deleteRecord(sP);
                break;
            case 6:
                numberOfAccesses++;
                fprintf(stderr,"The total number of Accesses is %d\n\n", numberOfAccesses);
                break;
            case 7:
                exit(0);
            default:
                printf("Error: Input was not a valid selection.\n\n");
                break;
        }
    }
return 0;
}

int printAllRecords(struct structInit *structPointer){
    int i;
    structPointer = sSP;
    printf("All Records: \n");
    for(i=1;i<=recordNumber;i++){
    printf("Record Number: %d\n", i);
    fprintf(stderr, "Name = \%s\n", structPointer-> name);
        fprintf(stderr, "Fire Number = \%s\n", structPointer-> fireNumber);
        fprintf(stderr, "Street = \%s\n", structPointer-> street);
        fprintf(stderr, "City = \%s\n", structPointer-> city);
        fprintf(stderr, "State = \%s\n\n", structPointer-> state);
        structPointer++;
    }
    return 1;
}

int printSizeOfDatabase(struct structInit *structPointer) {
    int size = 0;
    int i;
    for (i=1;i<=recordNumber;i++) {
    size += sizeof(structPointer->name);
    size += sizeof(structPointer->fireNumber); 
    size += sizeof(structPointer->street);
    size += sizeof(structPointer->city);
    size += sizeof(structPointer->state);
    structPointer++;
        }
    fprintf(stderr, "The size of the database is %d bytes.\n\n", size);
    return size;
}

int addRecord(struct structInit *structPointer){
    char entryName;
    char entryFireNumber;
    char entryStreet;
    char entryCity;
    char entryState;
    recordNumber++;
    struct structInit *theStruct;
    theStruct = (struct structInit *) malloc ((recordNumber+1) * sizeof(struct structInit));
    int i;
    for (i=1;i<recordNumber;i++){
        memcpy(theStruct->name,structPointer->name,51);
        memcpy(theStruct->fireNumber,structPointer->fireNumber,11);
        memcpy(theStruct->street,structPointer->street,26);
        memcpy(theStruct->city,structPointer->city,26);
        memcpy(theStruct->state,structPointer->state,26);
        /*if(i==recordNumber){
            theStruct++;}
        else{
            theStruct++;
            structPointer++;}*/
    theStruct++;
    structPointer++;
    }
    theStruct++;

    printf("Enter the Name of the New Record: \n");
    scanf("%s",&entryName);
    memcpy(theStruct->name,&entryName,51);
    printf("Enter the Fire Number of the New Record: \n");
    scanf("%s",&entryFireNumber);
    memcpy(theStruct->fireNumber,&entryFireNumber,11);
    printf("Enter the Street of the New Record: \n");
    scanf("%s",&entryStreet);
    memcpy(theStruct->street,&entryStreet,26);
    printf("Enter the City of the New Record: \n");
    scanf("%s",&entryCity);
    memcpy(theStruct->city,&entryCity,26);
    printf("Enter the State of the New Record: \n");
    scanf("%s",&entryState);
    memcpy(theStruct->state,&entryState,26);
    structPointer=theStruct;
    printf("Record has been added.\n\n");
    return 0;
}

int deleteRecord(struct structInit *structPointer){
    struct structInit *anotherStruct;
    anotherStruct = (struct structInit *) malloc ((recordNumber+1) * sizeof(struct structInit));
    int i;
    for(i=0;i<5;i++){
    memcpy(anotherStruct->name,structPointer->name,51);
    memcpy(anotherStruct->fireNumber,structPointer->fireNumber,11);
    memcpy(anotherStruct->street,structPointer->street,26);
    memcpy(anotherStruct->city,structPointer->city,26);
    memcpy(anotherStruct->state,structPointer->state,26);
    structPointer++;
    }
    structPointer=anotherStruct;
    recordNumber--;
    printf("Record has been deleted.\n\n");
    return 0;
}

Answer 1

一目了然：

%s的{{1}}格式说明符指定指向数组scanf的第一个元素的指针。
您正在将指针传递给一个字符。
这项计划并没有完全崩溃，这只是运气不好。

你想要

char

和其他输入类似。

将char entryName[51]; /* ... */ printf("Enter the Name of the New Record: \n"); scanf("%s", entryName);替换为memcpy - 您不应该从源对象外部复制任何内容。

如果您使用strncpy，则可以在展开表格时摆脱整个复制循环。

分配参数不会修改传入其值的变量的值这对于指针和其他所有内容都是如此如果要修改变量，请将指针传递给它：

realloc

你不需要在结构之间进行成员int addRecord(struct structInit **structPointer) { /* ... */ *structPointer = theStruct; /* ... */ } - 事实上你根本不需要memcpy，因为任务有效：

memcpy

您需要决定是否使用全局变量或参数特别是，struct structInit a = /* ... */; struct structInit b = /* ... */; a = b; /* OK */完全忽略其参数的值。

printAllRecords假设您的表中有五条记录。

您也可以将deleteRecord替换为：

printSizeOfDatabase

Answer 2

您可以在add函数中使用realloc。 typedef会使程序更容易阅读。请将此行添加到mydata.h的末尾

re.sub(r'^http://www.mega.pk/(\w+)-.*', lambda x: x.group(), line)

然后在main（）之前变成

structInit * sP; structInit * sSP;

然后printAllRecords成为： int printAllRecords（structInit * structPointer）

然后打开调试器并阅读消息。

Error when adding another record to dynamic memory database

2 个答案: