How do you define variable size array in c?

Answer 1

Array is the set of multiple values while variable is used to store a single value at a time.

Arrays have subscript while variable doesn't have a subscript.

Syntax of declaring array and variable is different.

For variable:

data_type list of variables;

For array:

Data_type variable1[size], variablen[size];

Answer 2

Not possible, use pointers instead, eg:

typedef struct MyIntArr {

. int *ptr;

. size_t size;

} MyIntArr;

#define EmptyMyIntArr {NULL, 0}

int *AccessMyIntArr (MyIntArr *arr, size_t index)

{

. if (index>=arr.size) {

. . size_t newsize= index+1;

. . int *newptr= NULL;

. . if (newsize < arr->size * 2) newsize= arr->size * 2;

. . newptr= realloc (arr->ptr, newsize);

. . if (newptr==NULL) exit (33);

. . arr->ptr= newptr;

. . arr->size= newsize;

. }

. return arr->ptr + index;

}

MyIntArr a = EmptyMyIntArr;

*AccessMyIntArr (&a, 72) = 100;

*AccessMyIntArr (&a, 100) = *AccessMyIntArr (&a, 72) + 1;

Answer 3

by using malloc functoin