Insert structure arrays dynamic in C. Exited, segmentation fault

Question

I have a problem with structure arrays, to insert dynamic values.

Cannot insert values into dynamic arrays, response "Exited, segmentation fault".

Can anyone help me, that's problem. Thank you ............................................................................................................................................................................................................................................................................................................................

Syntax:

#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <stdlib.h>
#define FLUSH while (getchar() != '\n') 

typedef struct{
    char *Name;
    int Qty;
} Item;

static void insert(Item* i, char *name, int qty)
{
    i->Name = name;
    i->Qty = qty;
}

int main() {

    int storage = 0, menu;
    printf("Temporary Storage\n");

    //Input storage amount
    bool isInputStorage = true;
    while (isInputStorage) {
        printf("Input Storage amount [1..10]: ");
        scanf("%d", &storage);

        if (storage <= 10 && storage >= 1) {
            isInputStorage = false;
        }
        else {
            printf("\n[!]Please enter numbers [1..10] for Storage amount.\n\n");
        }
        FLUSH;
    }

    Item *dataItems;

    //Input Menu
    bool isInputMenu = true;
    while (isInputMenu) {

        printf("\n\nMenu\n");
        printf("=============\n");
        printf("1. Add items\n");
        printf("4. Exit\n");
        printf("Choose Menu [1..4]: ");
        scanf("%d", &menu);

        if (menu >= 1 && menu <= 4) {

            if (menu == 1) {
                char* name;
                int qty;

                //Insert to arrays storage
                int currentStorageAmount = sizeof(dataItems) / sizeof(dataItems[0]);
                if (currentStorageAmount >= storage) {
                    printf("Storage is Full");
                }
                else {

                    printf("Input name of Item : ");
                    scanf("%s", name);

                    bool isQty = true;
                    while (isQty) {
                        FLUSH;
                        printf("Input qty of Item : ");

                        int correctQty = scanf("%d", &qty);

                        if (correctQty == 1) {
                            isQty = false;
                        }
                        else {
                            printf("\n[!]Please enter number for Qty!\n\n");
                        }

                    }

                    //action to insert
                    insert(&dataItems[currentStorageAmount], name, qty);

                }
            }
            else if (menu == 4) {
                printf("\nThank you for using this application.\n");
                isInputMenu = false;
            }
        }
        else {
            printf("\n[!]Please enter numbers [1..4] for choose Menu.");
        }

        menu = 0;
        FLUSH;
    }

    system("pause");
    return 0;
}

Result:

Temporary Storage
Input Storage amount [1..10]: 4

Menu
=============
1. Add items
4. Exit
Choose Menu [1..4]: 1
Input name of Item : test
Input qty of Item : 5
exited, segmentation fault

dataItems is not initialized to any memory location and could be located anywhere in memory, allocate the "dynamic array", either using Item dataItems[storage] or Item *dataItems = malloc(sizeof(Item) * storage) and check dataItem before using. — dvhh
– dvhh, Commented Jul 26, 2019 at 4:56
You can't do char* name;...scanf("%s", name); because you haven't created any memory for the name to go - in fact you haven't initialized the pointer to ANYTHING. It's the same problem that @dvhh mentioned. Basically you need to initialize ALL your variables. — Jerry Jeremiah
– Jerry Jeremiah, Commented Jul 26, 2019 at 5:46

Dmitry Kuzminov · Accepted Answer · 2019-07-26 05:32:06Z

3

You are asking about arrays but there is no one array in your code...

What you really have is the pointer to Item. This means three things:

You have not initialized this pointer, and it points to somewhere. So the expression &dataItems[currentStorageAmount] gives you a random position in memory that leads you to the segmentation fault.
The expression sizeof(dataItems) / sizeof(dataItems[0]) gives you something different from what you expect: size of the pointer divided to size of the structure. In other words it is zero.
You need to allocate memory before using the dataItems.

edited Jul 26, 2019 at 5:32

answered Jul 26, 2019 at 4:44

Dmitry Kuzminov

6,6508 gold badges25 silver badges50 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

gx16 · Accepted Answer · 2019-07-26 06:09:08Z

0

I check the code with GDB, the error is at line 65,

scanf("%s", name);

you have declared a pointer char* name, but you have not allocated its heap memory yet. The correct solution is to change the line,

char *name

To

char* name = malloc(128);

Then, the code is running.

answered Jul 26, 2019 at 6:09

gx16

1921 silver badge11 bronze badges

Collectives™ on Stack Overflow

Insert structure arrays dynamic in C. Exited, segmentation fault

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related