C, Segmentation fault while using dynamic array in struct - c

Question

I'm trying to add new element to dynamic array in C (I know that I must free all memory. I will do it later), but I get this error every time:
But, what is strange, if I compile from terminal, like that, code works properly.
So, where is the error and how i can beat it?
Thank you!
All my code:
main.c
#include <stdio.h>
#include <stdlib.h>
typedef struct vector
{
int size;
int *array;
int alreadyIn;
}vector;
vector *vectorInit(int size)
{
vector *newVec = (vector *)malloc(sizeof(vector));
if(!newVec){printf("No memory!\n"); return NULL;}
newVec->size = size;
newVec->array = (int *)malloc(size * sizeof(int));
return newVec;
}
void allocNewMemory(vector *vect, int howMuch)
{
vect->array = (int *)realloc(vect->array ,(vect->size + howMuch) * sizeof(int));
vect->size += howMuch;
}
void pushBack(vector *vect, int number)
{
int howMuch = 5;
if(vect && vect->alreadyIn < vect->size)
{
vect->array[vect->alreadyIn] = number;
vect->alreadyIn++;
}
else
{
printf("Alloc new memory for %d elements...\n", howMuch);
allocNewMemory(vect, howMuch);
pushBack(vect, number);
}
}
void printVector(vector *vect)
{
for (int i = 0; i < vect->alreadyIn; i++)
{
printf("%d ", vect->array[i]);
}
printf("\n");
}
int main()
{
int startSize = 4;
vector * vec = vectorInit(startSize);
for (int i = 0; i < 6; i++)
{
pushBack(vec, i+1);
}
printVector(vec);
return 0;
}

Answer 1

You never initialize the alreadyIn member in the structure. That means its value will be indeterminate (and seemingly garbage or random).
You need to explicitly initialize it to zero:
vector *vectorInit(int size)
{
vector *newVec = malloc(sizeof(vector));
if(!newVec)
{
printf("No memory!\n");
return NULL;
}
newVec->size = size;
newVec->array = malloc(size * sizeof(int));
newVec->alreadyIn = 0; // Remember to set this to zero
return newVec;
}
This problem should have been easy to detect in the debugger.
Also note that I removed the casts from malloc. One should not cast the result of malloc, or really any function returning void *.