getting runtime error in a C program

Question

Touching C after a long time. I am getting a run time error in the following code. The IDE[C-Free] which I am using is not showing the exact error but it shows 'StackMin.exe' has stopped working.

Here, I am using two structures, struct stack is for stack and struct AdvanedStack is for storing two stacks. In the end I want to print the capacity of both the stacks which are in the AdvancedStack

Code is :

#include<stdio.h>

struct stack {
    int capacity;
    int top;
    int *array;
  };

struct AdvancedStack{

    struct stack* elementStack;
    struct stack* minStack; 

};


struct stack* createStack()
{
    struct stack* myStack= (struct stack*)malloc(sizeof(struct stack));
    myStack->capacity=5;
    myStack->top=-1;
    myStack->array= malloc(myStack->capacity * sizeof(int));

    return myStack;

}

struct AdvancedStack* createAdvancedStack()
{
  struct AdvancedStack *myStack = (struct AdvancedStack*)malloc(sizeof(struct AdvancedStack));
    myStack->elementStack=createStack();
    myStack->minStack=createStack();
}

int main()
{
    struct AdvancedStack* advStack = createAdvancedStack();

   printf("%d",advStack->elementStack->capacity);
    printf("%d",advStack->minStack->capacity);
}

Community · Accepted Answer · 2017-05-23 11:50:52Z

3

You forgot to return myStack from the createAdvancedStack() function.

struct AdvancedStack* createAdvancedStack()
{
    struct AdvancedStack *myStack = malloc(sizeof(struct AdvancedStack)); //Don't cast the result of malloc

    myStack->elementStack=createStack();
    myStack->minStack=createStack();

    return myStack; //You forgot this
}

Read this to know why you should not cast the result of malloc.

edited May 23, 2017 at 11:50

CommunityBot

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answered Mar 1, 2015 at 10:31

Spikatrix

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4 Comments

Vikas Mangal Over a year ago

Adding the return statement worked. Thanks for that. But is there any specific reason why to avoid casting the result of malloc here. Does it make any difference?

Leonard Michlmayr Over a year ago

Also, main should return a value or call exit().

David Ranieri Over a year ago

Read the link, there are several reasons.

Spikatrix Over a year ago

@VikasMangal , Read the link in my answer to know the answer.

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