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Loops: for, while, do-while — C++ MCQs

1. What will be the output of the following code?
for(int i = 1; i <= 3; i++)
cout << i << " ";

(A) 1 2 3


(B) 0 1 2


(C) 2 3 4


(D) Error



2. What is the output of this code?
int i = 1;
while(i <= 3) {
cout << i;
i++;
}

(A) Error


(B) 0 1 2


(C) Infinite loop


(D) 1 2 3



3. What will the following code display?
int i = 3;
do {
cout << i;
i–;
} while(i > 0);

(A) 3 2 1


(B) 2 1 0


(C) 1 2 3


(D) Error



4. What will happen when this code runs?
int i = 1;
while(i <= 5);
{
cout << i;
i++;
}

(A) 1 2 3 4 5


(B) Infinite loop


(C) Prints 1 once


(D) Error



5. What is the output?
for(int i = 1; i < 5; i += 2)
cout << i;

(A) 1 3


(B) 1 2 3 4


(C) 2 4


(D) 0 1 2 3



6. What will this code print?
int i = 0;
while(i < 3) {
cout << i;
i++;
}

(A) 0 1 2


(B) 1 2 3


(C) 1 2


(D) Error



7. What is the output?
int i = 1;
do {
cout << i;
i += 2;
} while(i < 6);

(A) 1 2 3 4 5


(B) 1 3


(C) 1 3 5


(D) Error



8. Find the output:
for(int i = 0; i < 5; i++)
if(i % 2 == 0)
cout << i;

(A) 0 1 2 3 4


(B) 1 3


(C) 0 2 4


(D) 2 4



9. What happens in this loop?
int i = 0;
while(i < 0)
cout << "Hello";

(A) Prints Hello infinitely


(B) Prints Hello once


(C) No output


(D) Error



10. What will the following program print?
int i = 1;
do {
cout << i;
i–;
} while(i > 0);

(A) 1


(B) 1 0


(C) 1 −1


(D) Infinite loop



11. What will be displayed?
for(int i = 5; i >= 1; i–)
cout << i;

(A) 1 2 3 4 5


(B) 5 4 3 2 1


(C) 5 3 1


(D) Error



12. What is the output?
int i = 1;
while(i <= 3) {
cout << i;
i = i + 2;
}

(A) Infinite loop


(B) 1 2 3


(C) 2 3


(D) 1 3



13. What will be printed?
for(int i = 0; i < 3; i++)
for(int j = 0; j < 2; j++)
cout << i << j << " ";

(A) 00 01 10 11 20 21


(B) 00 10 20 01 11 21


(C) 01 11 21


(D) Error



14. Output of the code below:
int i = 1;
do {
cout << "Hi";
i++;
} while(i < 1);

(A) Hi


(B) No output


(C) Infinite loop


(D) Error



15. What is the output?
int i = 0;
while(i != 5) {
cout << i;
i++;
}

(A) 0 1 2 3 4


(B) 1 2 3 4 5


(C) 0 1 2 3 4 5


(D) Error



16. What happens?
for(int i = 1; i <= 3; i++);
cout << i;

(A) Prints 1 2 3


(B) Error: i undeclared


(C) Infinite loop


(D) Prints 3



17. Output of the loop:
int i = 1;
do {
cout << i;
i += 3;
} while(i < 10);

(A) 1 4 7 10


(B) 1 3 5 7 9


(C) 1 4 7


(D) Error



18. What is the result?
int i = 5;
while(–i > 0)
cout << i;

(A) 5 4 3 2 1


(B) 4 3 2 1


(C) 3 2 1


(D) Infinite loop



19. What will the following code do?
for(int i = 1; i <= 5; i++)
if(i == 3)
break;
cout << i;

(A) 1 2


(B) 3


(C) 1


(D) Error



20. What is the output?
int i = 0;
while(i < 5) {
if(i == 3) break;
cout << i;
i++;
}

(A) 0 1 2


(B) 0 1 2 3


(C) 1 2 3


(D) Error



21. What will print?
for(int i = 1; i <= 5; i++) {
if(i == 2) continue;
cout << i;
}

(A) 1 2 3 4 5


(B) 1 3 4 5


(C) 2 3 4 5


(D) 1 2



22. What will be printed?
int i = 0;
do {
i++;
if(i == 2) continue;
cout << i;
} while(i < 4);

(A) 1 3 4


(B) 1 2 3


(C) 1 3


(D) Error



23. What happens?
int i = 1;
while(true) {
cout << i;
if(i == 3) break;
i++;
}

(A) 3


(B) Infinite loop


(C) Error


(D) 1 2 3



24. What is the output?
for(int i = 2; i <= 6; i += 2)
cout << i;

(A) 2 4 6


(B) 2 3 4 5 6


(C) 2 4


(D) 4 6



25. What will this code print?
int i = 5;
while(i– > 0)
cout << i;

(A) 5 4 3 2 1 0


(B) 4 3 2 1 0


(C) 4 3 2 1


(D) Infinite loop



26. Output of the following:
for(int i = 0; i < 3; i++) {
for(int j = 0; j < 2; j++)
cout << j;
}

(A) 010101


(B) 012012


(C) 0102


(D) Error



27. What will print?
int i = 1;
while(i <= 5)
cout << i++;

(A) Infinite


(B) 0 1 2 3 4


(C) 1 2 3 4 5


(D) Error



28. Output of this code:
int i = 10;
do {
cout << i;
i -= 4;
} while(i > 0);

(A) 10 6 2


(B) 10 5 0


(C) 10 6 2 -2


(D) Error



29. What happens in this loop?
for(int i = 1; i <= 3; i++)
for(int j = 1; j <= i; j++)
cout << "*";

(A) ***


(B) * ** ***


(C) * * *


(D) Error



30. What will be printed?
int i = 1;
do {
cout << i;
i++;
} while(i <= 0);

(A) 1


(B) 1 2


(C) 0


(D) No output



31. What is the result?
for(int i = 1; i <= 10; i++)
if(i % 2 == 0) cout << i;

(A) 1 2 3 4


(B) 1 3 5 7 9


(C) 0 2 4 6 8


(D) 2 4 6 8 10



32. What will this code output?
int i = 0;
while(i++ < 3)
cout << i;

(A) 0 1 2


(B) 1 2 3


(C) 1 2


(D) Error



33. What is the output?
int i = 3;
while(–i)
cout << i;

(A) 3 2 1


(B) 2 1 0


(C) 2 1


(D) Infinite loop



34. Find the output:
int i = 2;
do {
cout << i;
i = i + 2;
} while(i <= 8);

(A) 2 4 6 8


(B) 2 4 6


(C) 4 6 8


(D) 2 4 6 8 10



35. What is the result of this program?
int i = 1;
while(i <= 5) {
cout << i;
i += 2;
}

(A) 1 3 5


(B) 1 2 3 4 5


(C) 2 4 6


(D) Infinite loop



36. What will be the output of the following code?
int x = 2;
switch(x) {
case 1: cout << "One"; break;
case 2: cout << "Two"; break;
case 3: cout << "Three"; break;
}

(A) One


(B) Two


(C) Three


(D) Error



37. What will the following program print?
int num = 5;
switch(num) {
case 1: cout << "A"; break;
case 5: cout << "B"; break;
default: cout << "C";
}

(A) A


(B) C


(C) B


(D) Error



38. What will be printed?
int x = 10;
switch(x) {
case 5: cout << "Five"; break;
case 10: cout << "Ten"; break;
default: cout << "None";
}

(A) Five


(B) Ten


(C) None


(D) Error



39. What happens when the code runs?
int x = 3;
switch(x) {
case 1: cout << "A";
case 2: cout << "B";
case 3: cout << "C";
}

(A) C


(B) ABC


(C) BC


(D) C followed by nothing



40. What will this code output?
int val = 2;
switch(val) {
case 1: cout << "X"; break;
case 2: cout << "Y";
case 3: cout << "Z"; break;
default: cout << "W";
}

(A) Y


(B) YZ


(C) YZW


(D) Error



41. Identify the output:
int x = 4;
switch(x) {
case 1: cout << "A"; break;
case 2: cout << "B"; break;
default: cout << "C";
}

(A) A


(B) B


(C) C


(D) Error



42. Which statement is true about the following code?
int x = 5;
switch(x) {
case 5: cout << "Hello";
case 6: cout << "World";
}

(A) HelloWorld


(B) Hello


(C) World


(D) Error



43. What will be printed?
int a = 1;
switch(a + 1) {
case 1: cout << "One"; break;
case 2: cout << "Two"; break;
default: cout << "Other";
}

(A) One


(B) Two


(C) Other


(D) Error



44. What is the output?
int n = 0;
switch(n) {
case 0: cout << "Zero"; break;
case 1: cout << "One"; break;
default: cout << "Other";
}

(A) Zero


(B) One


(C) Other


(D) Error



45. What will happen when this code executes?
char ch = 'B';
switch(ch) {
case 'A': cout << "Apple"; break;
case 'B': cout << "Banana"; break;
default: cout << "Other";
}

(A) Apple


(B) Error


(C) Other


(D) Banana



46. What will the following output?
int n = 2;
switch(n * 2) {
case 2: cout << "Two"; break;
case 4: cout << "Four"; break;
default: cout << "None";
}

(A) Two


(B) Four


(C) None


(D) Error



47. What happens in this case?
int n = 1;
switch(n) {
case 1:
case 2: cout << "Match"; break;
default: cout << "No match";
}

(A) Match


(B) No match


(C) Error


(D) Nothing



48. Identify the error in this code:
float x = 1.5;
switch(x) {
case 1: cout << "One"; break;
case 2: cout << "Two"; break;
}

(A) switch expression must be integer or enum type


(B) Missing default


(C) Missing break


(D) No error



49. What will be printed?
int num = 7;
switch(num) {
case 5: cout << "Five"; break;
case 7: cout << "Seven"; break;
default: cout << "None";
}

(A) Five


(B) Seven


(C) None


(D) Error



50. What will this code produce?
int val = 9;
switch(val) {
case 10: cout << "Ten"; break;
case 11: cout << "Eleven";
default: cout << "Default";
}

(A) Ten


(B) Eleven


(C) Default


(D) ElevenDefault



51. What is the output of the following?
int n = 3;
switch(n) {
case 1: cout << "One";
case 2: cout << "Two";
case 3: cout << "Three";
default: cout << "Done";
}

(A) ThreeDone


(B) Done


(C) OneTwoThree


(D) Three only



52. What will happen here?
int x = 10;
switch(x) {
case 5: cout << "Five";
case 10: cout << "Ten"; break;
case 15: cout << "Fifteen";
}

(A) Ten


(B) TenFifteen


(C) FiveTen


(D) Error



53. What is the output?
int x = 1;
switch(x) {
case 0: cout << "Zero"; break;
case 1: cout << "One";
default: cout << "End";
}

(A) OneEnd


(B) One


(C) End


(D) Error



54. What happens when this code runs?
int x = 2;
switch(x) {
case 1: cout << "Case1";
case 2: cout << "Case2";
case 3: cout << "Case3";
default: cout << "Default";
}

(A) Default


(B) Case2


(C) Case3Default


(D) Case2Case3Default



55. What will be printed?
int a = 4;
switch(a) {
case 2: cout << "Two"; break;
case 4: cout << "Four"; break;
case 6: cout << "Six"; break;
default: cout << "Other";
}

(A) Two


(B) Four


(C) Six


(D) Other



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