Lesson 2 (Q&A)

 Control Statments

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Part A: Multiple Choice Questions

(1 Marks Each)

1. Which of the following is a declaration statement?
   (a) int x;
   (b) printf("%d", x);
   (c) if(x>0)
   (d) for(i=0; i<5; i++)
   Ans:- (a) int x;

2. Which library provides printf() and scanf()?
   (a) conio.h
   (b) stdio.h
   (c) string.h
   (d) math.h
   Ans:- (b) stdio.h

3. What does %f represent in printf()?
   (a) Integer
   (b) Character
   (c) Float
   (d) String
   Ans:- (c) Float

4. The correct syntax for declaring a constant is:
   (a) int const MAX=100;
   (b) const int MAX=100;
   (c) constant int MAX=100;
   (d) int MAX=constant 100;
   Ans:- (b) const int MAX=100;

5. Which function is used for unformatted input of a character?
   (a) putchar()
   (b) getchar()
   (c) gets()
   (d) scanf()
   Ans:- (b) getchar()

6. Which function displays a string followed by newline?
   (a) puts()
   (b) putchar()
   (c) printf()
   (d) getc()
   Ans:- (a) puts()

7. Which of the following is unsafe in modern C?
   (a) printf()
   (b) gets()
   (c) scanf()
   (d) puts()
   Ans:- (b) gets()

8. An expression statement always produces:
   (a) condition
   (b) loop
   (c) value
   (d) function
   Ans:- (c) value

9. Which is an example of a conditional statement?
   (a) for
   (b) while
   (c) if
   (d) continue
   Ans:- (c) if

10. Which loop executes at least once?
    (a) for
    (b) while
    (c) do...while
    (d) switch
    Ans:- (c) do...while

11. Which jump statement ends a function?
    (a) break
    (b) goto
    (c) continue
    (d) return
    Ans:- (d) return

12. What will break do in a loop?
    (a) Skip next statement
    (b) Exit loop immediately
    (c) Jump to label
    (d) Continue loop
    Ans:- (b) Exit loop immediately

13. What will continue do in a loop?
    (a) Exit program
    (b) Skip current iteration
    (c) Jump to end
    (d) Restart program
    Ans:- (b) Skip current iteration

14. Which statement allows multi-way branching?
    (a) if
    (b) for
    (c) switch
    (d) goto
    Ans:- (c) switch

15. Which symbol is used before variables in scanf()?
    (a) $
    (b) *
    (c) &
    (d) %
    Ans:- (c) &

16. Example of increment expression:
    (a) x=5;
    (b) x++;
    (c) x=y+5;
    (d) if(x>y)
    Ans:- (b) x++;

17. Which operator is used in declaration syntax?
    (a) =
    (b) ;
    (c) ,
    (d) :
    Ans:- (a) =

18. Which function is used to display a single character?
    (a) putchar()
    (b) puts()
    (c) printf()
    (d) getc()
    Ans:- (a) putchar()

19. What will printf("Age: %d",15); display?
    (a) Age: %i
    (b) Age: %f
    (c) Age: 15
    (d) Age: d
    Ans:- (c) Age: 15

20. Which statement is used to jump to another labeled part of program?
    (a) break
    (b) continue
    (c) return
    (d) goto
    Ans:- (d) goto

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Part B: Very Short Answer Questions (1 Mark Each)

1. Write the syntax of variable declaration.
   Ans:- datatype variable_name; (e.g., int x;)

2. Which header file provides input/output functions in C?
   Ans:- stdio.h

3. What does %c format specifier represent?
   Ans:- A single character.

4. Give one example of a declaration statement.
   Ans:- int a;

5. Which function reads a string including spaces?
   Ans:- gets()

6. Which function is preferred instead of gets() in modern C?
   Ans:- fgets()

7. Give an example of an expression statement.
   Ans:- x = y + 5;

8. Which conditional statement allows multiple cases?
   Ans:- switch statement.

9. Write syntax of a for loop.
   Ans:- for(initialization; condition; increment/decrement) { //code }

10. Which statement is used to terminate a loop immediately?
    Ans:- break;

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Part C: Short Answer Questions (4 Marks Each)

Q1. Define declaration statement with one example.
Ans:- A declaration statement tells the compiler about the type of a variable.
Example: int age;

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Q2. Differentiate between formatted and unformatted I/O statements.
Ans:-

• Formatted I/O: Uses format specifiers. Example: printf(), scanf().

• Unformatted I/O: Works directly with characters/strings. Example: getchar(), putchar(), gets(), puts().

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Q3. Explain the use of scanf() with an example.
Ans:- scanf() is used to take input from the user.
Example: scanf("%d",&num);

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Q4. What is the difference between putchar() and puts()?
Ans:-

• putchar() → prints one character.

• puts() → prints a full string with a new line at the end.

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Q5. Write the syntax and example of printf() function.
Ans:-
Syntax: printf("format specifier", variable);
Example: printf("Age: %d", 20);

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Q6. Explain increment and decrement operators with examples.
Ans:-

• Increment (++) increases value by 1. Example: x++;

• Decrement (--) decreases value by 1. Example: x--;

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Q7. Write syntax and example of if…else statement.
Ans:-
Syntax:

if(condition) {
   //code
} else {
   //code
}

Example:

if(x>0)  
   printf("Positive");  
else  
   printf("Negative");

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Q8. Differentiate between while loop and do...while loop.
Ans:-

• while loop: checks condition first, then runs code.

• do...while loop: runs code once first, then checks condition.

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Q9. Write a short note on break and continue statements.
Ans:-

• break → exits the loop immediately.

• continue → skips the current step and goes to the next loop cycle.

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Q10. Why is gets() function unsafe in C?

Ans:- Because it does not check input size. This may cause buffer overflow, which is unsafe

Part D: Long Answer Questions (8 Marks Each)

Q1. Explain declaration statements in C with syntax and examples.
Ans:-
Declaration statements are used to create variables in C. They tell the compiler the type of data and name of the variable so that memory can be given.

Syntax:

datatype variable_name;

Examples:

int age;        // integer variable  
float marks;    // decimal value variable  
char grade;     // character variable  

These help the compiler to know what type of value will be stored in each variable.

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Q2. Describe formatted input/output functions (printf() and scanf()) with examples.
Ans:-

• printf(): Used to display (print) output in a formatted way.
  Example:

printf("Name: %s, Age: %d", name, age);

• scanf(): Used to take (read) input in a formatted way.
  Example:

scanf("%d", &age);

Both functions use format specifiers like:

• %d → integer

• %f → float

• %c → character

• %s → string

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Q3. Differentiate between formatted and unformatted I/O statements in detail with examples.
Ans:-

Formatted I/O	Unformatted I/O
Uses format specifiers	Does not use format specifiers
Works with integers, floats, characters, and strings	Works directly with characters/strings
Examples: printf(), scanf()	Examples: getchar(), putchar(), gets(), puts()

Examples:

// Formatted I/O
scanf("%d", &num);  
printf("Average = %f", avg);

// Unformatted I/O
char ch = getchar();  
puts("Hello World");

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Q4. Explain different types of control statements in C with suitable examples.
Ans:-
Control statements are used to control the flow of program execution. There are 3 types:

1. Conditional Statements (Decision making):

   • if, if-else, switch
     Example:

   if(x > 0)
       printf("Positive");
   else
       printf("Negative");
   

2. Looping Statements (Repetition):

   • for, while, do...while
     Example:

   for(i=0; i<5; i++)
       printf("%d", i);
   

3. Jump Statements (Change program flow):

   • break, continue, goto, return
     Example:

   for(i=0; i<10; i++) {
       if(i == 5) break;  // loop stops when i=5
   }
   

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Q5. What are jump statements in C? Explain break, continue, goto, and return with examples.
Ans:-
Jump statements are used to change the normal flow of a program.

1. break: Exits from a loop or switch immediately.

   for(i=1;i<=5;i++) {
       if(i==3) break;
       printf("%d ",i);  // prints 1 2
   }
   

2. continue: Skips the current loop iteration and moves to the next one.

   for(i=1;i<=5;i++) {
       if(i==3) continue;
       printf("%d ",i);  // prints 1 2 4 5
   }
   

3. goto: Jumps to a labeled statement.

   goto label;  
   printf("This will be skipped");  
   label: printf("This is goto statement");  
   

4. return: Ends a function and sends control back to the calling function.

   int sum(int a, int b) {
       return a + b;
   }