CODEWITHSUNDEEP
cmemoryrealloc
William McCarty
William McCarty

Reputation: 839

C realloc usage

I'm trying to dynamically increase memory of an int array, However I'm having issues getting it to work. It isn't expanding and adding more elements to the array, I'm not sure what I'm doing wrong. Please help!

int* fibs = NULL;

void genFibs(){
    int i = 1,curSize = 0,curNum = 0;
    int flag = 1;
    while(flag){
        if(curSize != 0 &&curSize != 1){
            curNum = fibs[curSize-2]+fibs[curSize-1];
        }else if(curSize-1 == 1){
            curNum = fibs[curSize-1]+fibs[curSize-1];
        }else{
            curNum = 1;
        }
        if(curNum<=10){
            curSize++;
            fibs = (int*)realloc(fibs,curSize*sizeof(int));
            fibs[curSize-1] = curSize;
        }else{
            flag = 0;
        }
    }
  }
}

void printFibs(){
    int size = sizeof(fibs)/sizeof(int);
    int i = 0;
    for(i = 0;i<size;i++){
        printf("%d is: %d\n",i,fibs[i]);
    }
}

Upvotes: 0

Views: 207

Answers (2)

Xaqq
Xaqq

Reputation: 4386

Well, your print code is wrong. sizeof(fibs) will always be evaluated as sizeof(int *) because its just a pointer.

You have to find a way to pass the size to your print function. It could be, for example the first value of your array. But this is implementation detail and it's up to you.

EDIT: Changed sizeof(void *) to sizeof(int *) because pointer size may vary, as pointed out by pmg.

Upvotes: 5

Joe
Joe

Reputation: 6777

sizeof(fibs) is the size of the pointer fibs which is constant, therefore your printing function will always print the same number of elements

Upvotes: 1

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