# Languages-C & C Plus Plus [3i Infotech Placement]: Sample Questions 338 - 339 of 354

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## Question 338

C & C Plus Plus
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### Describe in Detail

Essay▾

What is the output of the following program?

1. `main ()`
2. `{`
3. `    struct student`
4. `    {`
5. `        char name[30];`
6. `        struct date dob;`
7. `    }stud;`
8. `    struct date`
9. `    {`
10. `        int day, month, year;`
11. `    };`
12. `    scanf ( “%s%d%d%d” ,stud. Rollno, &student. Dob. Day, &student. Dob. Month, &student. Dob. Year);`
13. `}`

### Explanation

Compiler Error: Undefined structure “date”

In the program

 struct student{char name [30] ;struct date dob;} stud; Inside the struct definition of ‘student’ the member of type struct date is given.The compiler doesn՚t have the definition of date structure (forward reference is not allowed in C in this case)So, it issues an error

## Question 339

C & C Plus Plus
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### Describe in Detail

Essay▾

For the following C program

1. `#define AREA (x) (3.14 ⚹x ⚹x)`
2. `main ()`
3. `{`
4. `    float r1 =6.25, r2 =2.5, a;`
5. `    a =AREA (r1);`
6. `    printf ( “ Area of the circle is %f”, a);`
7. `    a =AREA (r2);`
8. `    printf ( “ Area of the circle is %f” ,a);`
9. `}`

What is the output?

### Explanation

• In the program
 #define AREA (x) (3.14 ⚹ x ⚹ x) Define the area () function float r1 = 6.25, r2 = 2.5, a; Define the float variable r1 = 6.25, r2 = 2.5 and a variable a = AREA (r1) ; Thus when the preprocessor runs,Here a = AREA (6.25) ;a = (3.14 ⚹ 6.25 ⚹ 6.25)a = 122.656250 printf ( “Area of the circle is % f” , a) ; Printf prints the area of the circle as 122.656250 a = AREA (r2) ; Similarly, a = AREA (2.5) ;a = (3.14 ⚹ 2.5 ⚹ 2.5)a = 19.625000 printf ( “Area of the circle is % f” , a) ; Printf print the Area of the circle is 19.625000

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