Error in memory allocation for array of structures

Question

I am working on this code:

struct box
{
    char word[200][200];
    char meaning[200][200];
    int count;
};

struct root {
    box *alphabets[26];
};
root *stem;
box *access;
void init(){
     //cout<<"start";
    for(int i = 0 ; i<= 25; i++){
        struct box *temp =(struct box*)( malloc(sizeof(struct box)*100));
        temp->count = 0;
        cout<<temp->count;
        stem->alphabets[i] = temp;
    }
    //cout<<" initialized";
}

It got compiled without errors, but during its execution it stops at the point where temp is allocated to stem->alphabets[i]. How to fix this?

stem is not initialized. Thus a crash. initialize access too. — Uchia Itachi
– Uchia Itachi, Commented Sep 14, 2013 at 13:22
Choose one C or C++ ? With C++, you have STL, to make you job lot easier. — P0W
– P0W, Commented Sep 14, 2013 at 13:26

Sergey Kalinichenko · Accepted Answer · 2013-09-14 13:23:28Z

6

Make stem a struct, not a pointer:

root stem; // No asterisk

Otherwise, there's no memory allocated to it, so dereferencing it is undefined behavior.

Of course you need to replace stem->alphabets[i] with stem.alphabets[i].

answered Sep 14, 2013 at 13:23

Sergey Kalinichenko

729k85 gold badges1.2k silver badges1.6k bronze badges

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

2 Comments

Uchia Itachi Over a year ago

You meant stem i guess.

Sergey Kalinichenko Over a year ago

@KarthikSivam You are welcome! If this solves your problem, consider accepting the answer by clicking the grey check mark next to it. This lets other visitors of the site know that you are no longer actively looking for an improved solution to this problem, and earns you a brand-new badge on Stack Overflow.

Erbureth · Accepted Answer · 2013-09-14 13:24:11Z

4

You need to allocate memory for the stem variable

root * stem = new root();

Don't forget to dealocate:

delete stem;

Better yet, read something about memory allocations in C++

answered Sep 14, 2013 at 13:24

Erbureth

3,4231 gold badge24 silver badges42 bronze badges

Comments

wholerabbit · Accepted Answer · 2013-09-14 14:02:36Z

3

stem and temp are two different variables. :) you are giving memory to temp and accessing stem.

edited Sep 14, 2013 at 14:02

wholerabbit

11.6k2 gold badges40 silver badges73 bronze badges

answered Sep 14, 2013 at 13:23

Dayal rai

6,63624 silver badges29 bronze badges

4 Comments

Dayal rai Over a year ago

I am habitual of this :) carry on guyz

wholerabbit Over a year ago

That was me -- although I'd swear the "you are giving memory to temp and accessing stem" wasn't there when I voted, it won't let me reverse until you edit. :(

wholerabbit Over a year ago

Ok -- spoofed that with a dud edit to get this travesty off my conscience. All apologies.

Dayal rai Over a year ago

@goldilocks chill man, and thanks and salute to your honesty :)

john · Accepted Answer · 2013-09-14 13:38:03Z

0

You are using pointers without initializing them first. The simple answer is not to use pointers in the first place. I can see no reason for pointers in the code you have posted.

struct box
{
    char word[200][200];
    char meaning[200][200];
    int count;
};

struct root {
    box alphabets[26];
};
root stem;

Much easier.

answered Sep 14, 2013 at 13:38

john

88.3k5 gold badges61 silver badges95 bronze badges

Collectives™ on Stack Overflow

Error in memory allocation for array of structures

4 Answers 4

2 Comments

Comments

4 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

2 Comments

Comments

4 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related