CBSE Class 11 - Computer Science - CH9 - Flow of Control (Sumita Arora Textbook Solutions)

Flow Of Control
(Sumita Arora) Textbook Solutions 7th Edn

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SHORT ANSWER QUESTIONS

Q1: What is null statement and a compound statement? What is the alternate name of the compound statement?

Answer: The simplest statement is null statement or empty statement. It is represented as just semicolon (;).
 e.g. ; // null statement

A compound statement is a sequence of statements enclosed by pair of braces ({}). Alternate name of the compound statement is block.


Q2: What is the significance of a null statement?

Answer: A null statement is useful where the language requires a statement but the program's logic does not.

e.g.  a program keeps on reading a value till it encounters a particular value or end-of-file.
  
while (cin >> val && val != required_vale) 

            ; 

Q3: What are the three constructs that govern statement flow?

Answer: sequence, selection and iteration


Q4: What is the significance of a test-condition in a loop?

Answer: The test-condition in a loop decides whether the loop-body will be executed or not based on the truth value. If the test-condition evaluates to true i.e., 1, the loop-body will execute, otherwise the loop is terminated.




Q5: What is a selection statement? Which selection statement does C++ provides?

Answer: The selection statement conditionally executes another statement (or block of statements) based on whether a specified expression is true. C++ provides two types of selection statements: if and switch.


Q6: Can a conditional operator replace an if statement always?

Answer: No in conditional operator usually replaces if statement but not always.


Q7: Correct the following code fragment:

if (x=1)
    k=100;
  else
 k=1O;

Answer: it should be if (x == 1)


Q8: What will be the output of the following code fragment?

  cin >> a;
  if (a=5)
 cout << "Five";
  else
 cout << "Not Five";
 
  if the input given is (1)7 (ii)5?

Answer: (Note: Please see if (a=5) assigns 5 to a. An assignment operator is used instead of equality operator. That's why if (condition) is always true.)
 (1) Five
 (2) Five


Q9: What will be the output of the following code fragment?

  int year;
  cin >> year;
  if (year%100 == 0)
 if(year%400 == 0)
  cout << "LEAP";
 else
  cout << "Not century year";
 
  if the input given is (i)2000 (ii)1900 (iii) 1971?

Answer:
          (i) LEAP
          (ii) Not century year
          (iii) No output


Q10: What will be the output of the following code fragment?

 int year;
 cin >> year;
 if (year%100 == 0)
  { 
  if(year%400 == 0)
   cout << "LEAP";
  } 
 else
  cout << "Not century year";
 
 if the input given is (i)2000 (11)1900 (iii) 1971?
 

Answer: (i) LEAP
              (ii) No output
             (iii) Not century year


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