Which of the following correctly represents a long double constant?

Which of the structure is incorrcet?

1 : struct aa
{
    int a;
    float b;
};

2 : struct aa
{
    int a;
    float b;
    struct aa var;
};

3 : struct aa
{
    int a;
    float b;
    struct aa *var;
};

Which of the structure is correct?

1 : struct book
{
    char name[10];
    float price;
    int pages;
};

2 : struct aa
{
    char name[10];
    float price;
    int pages;
}

3 : struct aa
{
    char name[10];
    float price;
    int pages;
}

1 : typedef long a;
extern int a c;
2 : typedef long a;
extern a int c;
3 : typedef long a;
extern a c;

A long double can be used if range of a double is not enough to accommodate a real number.

A float is 4 bytes wide, whereas a double is 8 bytes wide.

If the definition of the external variable occurs in the source file before its use in a particular function, then there is no need for an extern declaration in the function.

Size of short integer and long integer can be verified using the sizeof() operator.

Range of double is -1.7e-38 to 1.7e+38 (in 16 bit platform - Turbo C under DOS)

Size of short integer and long integer would vary from one platform to another.