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C++ Loops: Output Practice Questions

Practice C++ output basics with beginner-friendly questions on cout, variables, arithmetic expressions, and predicting console output in simple programs.

Instructions for Students

  1. Read the program carefully.
  2. Predict the output without running the code.
  3. Write your predicted output.
  4. Run the program to verify your answer.
  5. Understand why the output appears.
  6. Modify the code and predict the new output.

Contents

Section 1: While Loop

Question 1:

Task: Predict the output.

Code

int i = 2;
 
while (i <= 6)
{
    cout << i * i << " ";
    i++;
}

Question 2:

Task: Predict the output.

Code

int n = 20;
 
while (n >= 5)
{
    cout << n << " ";
    n -= 5;
}

Question 3:

Task: Predict the output.

Code

int i = 1;
 
while (i <= 4)
{
    cout << i << " ";
    i += 2;
}

Question 4:

Task: Predict the output.

Code

int i = 1;
 
while (i <= 3)
{
    cout << "CS" << i << " ";
    i++;
}

Question 5:

Task: Predict the output.

Code

int x = 2;
 
while (x <= 8)
{
    cout << x - 1 << " ";
    x += 3;
}

Question 6:

Task: Predict the output.

Code

int i = 4;
 
while (i >= 1)
{
    cout << i % 2 << " ";
    i--;
}

Question 7:

Task: Predict the output.

Code

int x = 1;
 
while (x <= 4)
{
    cout << x + 3 << " ";
    x++;
}

Question 8:

Task: Predict the output.

Code

int n = 3;
 
while (n > 0)
{
    cout << n * 2 << " ";
    n--;
}
 
cout << "Done";

Question 9:

Task: Predict the output.

Code

int x = 2;
int sum = 0;
 
while (x <= 8)
{
    sum += x;
    x += 2;
}
 
cout << sum;

Question 10:

Task: Predict the output.

Code

int n = 1;
int result = 1;
 
while (n <= 4)
{
    result += n * 3;
    n++;
}
 
cout << result;

Question 11:

Task: Predict the output.

Code

int x = 1;
 
while (x <= 8)
{
    if (x % 3 == 0)
        cout << x << " ";
 
    x++;
}

Question 12:

Task: Predict the output.

Code

int x = 10;
 
while (x > 0)
{
    x -= 3;
    cout << x << " ";
}

Question 13:

Task: Predict the output.

Code

int n = 2;
int count = 0;
 
while (n <= 12)
{
    if (n % 4 == 0)
        count++;
 
    n += 2;
}
 
cout << count;

Question 14:

Task: Predict the output.

Code

int x = 1;
int y = 8;
 
while (x <= 4)
{
    cout << x + y << " ";
    x++;
    y -= 2;
}

Question 15:

Task: Predict the output.

Code

int n = 1;
 
while (n <= 5)
{
    if (n == 3)
        cout << "Three ";
    else
        cout << n << " ";
 
    n++;
}

Question 16:

Task: Predict the output.

Code

int x = 2;
int product = 1;
 
while (x <= 6)
{
    product *= x;
    x += 2;
}
 
cout << product;

Question 17:

Task: Predict the output.

Code

int n = 5;
 
while (n >= 1)
{
    if (n % 2 == 1)
        cout << n * 2 << " ";
 
    n--;
}

Question 18:

Task: Predict the output.

Code

int x = 1;
int total = 0;
 
while (x <= 4)
{
    total += x * x;
    x++;
}
 
cout << total;

Question 19:

Task: Predict the output.

Code

int x = 1;
 
while (x <= 5)
{
    cout << x << " ";
 
    if (x % 2 == 0)
        cout << "Even ";
 
    x++;
}

Question 20:

Task: Predict the output.

Code

int n = 1;
int value = 2;
 
while (n <= 4)
{
    value += n;
    cout << value << " ";
    n++;
}

Question 21:

Task: Predict the output.

Code

int n = 246;
int sum = 0;
 
while (n > 0)
{
    sum += n % 10;
    n /= 10;
}
 
cout << sum;

Question 22:

Task: Predict the output.

Code

int n = 1357;
 
while (n > 0)
{
    cout << n % 10 << " ";
    n /= 100;
}

Question 23:

Task: Predict the output.

Code

int x = 1;
int y = 2;
 
while (x <= 4)
{
    y += x;
    x++;
 
    if (y > 5)
        cout << y << " ";
}

Question 24:

Task: Predict the output.

Code

int x = 1;
int count = 0;
 
while (x <= 10)
{
    if (x % 2 == 0 && x % 3 != 0)
        count++;
 
    x++;
}
 
cout << count;

Question 25:

Task: Predict the output.

Code

int x = 1;
 
while (x <= 4)
{
    int y = x;
 
    while (y > 0)
    {
        cout << y << " ";
        y--;
    }
 
    x++;
}

Question 26:

Task: Predict the output.

Code

int x = 1;
int y = 10;
 
while (x < y)
{
    cout << x * y << " ";
    x += 2;
    y -= 3;
}

Question 27:

Task: Predict the output.

Code

int n = 12345;
int result = 0;
 
while (n > 0)
{
    int digit = n % 10;
 
    if (digit % 2 == 1)
        result += digit;
 
    n /= 10;
}
 
cout << result;

Question 28:

Task: Predict the output.

Code

int x = 2;
int total = 0;
 
while (x <= 10)
{
    if (x % 4 == 0)
        total += x;
    else
        total -= 1;
 
    x += 2;
}
 
cout << total;

Question 29:

Task: Predict the output.

Code

int n = 5;
int result = 0;
 
while (n > 0)
{
    result = result * 2 + n;
    n -= 2;
}
 
cout << result;

Question 30:

Task: Predict the output.

Code

int n = 9876;
int reversed = 0;
 
while (n > 0)
{
    reversed = reversed * 10 + n % 10;
    n /= 10;
}
 
cout << reversed;

Question 31:

Task: Predict the output.

Code

int x = 1;
int result = 0;
 
while (x <= 6)
{
    if (x % 2 == 0)
        result += x * 2;
    else
        result += x;
 
    x++;
}
 
cout << result;

Question 32:

Task: Predict the output.

Code

int n = 1;
int sum = 0;
 
while (n <= 20)
{
    if (n % 4 == 0 || n % 6 == 0)
        sum += n;
 
    n++;
}
 
cout << sum;

Question 33:

Task: Predict the output.

Code

int n = 2;
int count = 0;
 
while (n <= 50)
{
    if (n % 7 == 0 && n % 2 == 0)
        count++;
 
    n += 2;
}
 
cout << count;

Section 1: do-while Loop

## Question 1:

Task: Predict the output.

### Code

int i = 2;
 
do
{
    cout << i * i << " ";
    i++;
}
while (i <= 6);

## Question 2:

Task: Predict the output.

### Code

int i = 1;
 
do
{
    cout << i << " ";
    i += 2;
}
while (i <= 9);

## Question 3:

Task: Predict the output.

### Code

int i = 5;
 
do
{
    cout << i << " ";
    i--;
}
while (i >= 1);

## Question 4:

Task: Predict the output.

### Code

int i = 1;
int sum = 0;
 
do
{
    sum += i;
    i++;
}
while (i <= 4);
 
cout << sum;

## Question 5:

Task: Predict the output.

### Code

int i = 2;
 
do
{
    cout << i * 3 << " ";
    i += 2;
}
while (i <= 10);

## Question 6:

Task: Predict the output.

### Code

int i = 10;
 
do
{
    cout << i << " ";
    i -= 3;
}
while (i > 0);

## Question 7:

Task: Predict the output.

### Code

int i = 1;
 
do
{
    cout << i * i * i << " ";
    i++;
}
while (i <= 4);

## Question 8:

Task: Predict the output.

### Code

int i = 1;
int count = 0;
 
do
{
    count++;
    i += 2;
}
while (i <= 10);
 
cout << count;

## Question 9:

Task: Predict the output.

### Code

int i = 1;
int sum = 0;
 
do
{
    if (i % 2 == 0)
    {
        sum += i;
    }
 
    i++;
}
while (i <= 6);
 
cout << sum;

## Question 10:

Task: Predict the output.

### Code

int i = 5;
 
do
{
    if (i % 2 == 0)
    {
        cout << i << " ";
    }
 
    i--;
}
while (i >= 1);

## Question 11:

Task: Predict the output.

### Code

int i = 1;
int x = 2;
 
do
{
    x += i;
    cout << x << " ";
    i++;
}
while (i <= 4);

## Question 12:

Task: Predict the output.

### Code

int i = 1;
int sum = 0;
 
do
{
    sum += i;
    i += 2;
}
while (i <= 7);
 
cout << sum;

## Question 13:

Task: Predict the output.

### Code

int i = 1;
int n = 10;
 
do
{
    cout << n - i << " ";
    i += 2;
}
while (i <= 5);

## Question 14:

Task: Predict the output.

### Code

int n = 246;
int count = 0;
 
do
{
    count++;
    n /= 10;
}
while (n > 0);
 
cout << count;

## Question 15:

Task: Predict the output.

### Code

int i = 1;
int result = 0;
 
do
{
    result = result * 10 + i;
    i++;
}
while (i <= 4);
 
cout << result;

## Question 16:

Task: Predict the output.

### Code

int i = 1;
int sum = 0;
 
do
{
    if (i % 3 == 0)
    {
        sum += i;
    }
 
    i++;
}
while (i <= 10);
 
cout << sum;

Section 3: Nested Loops

Question 1:

Task: Predict the output.

Code

int x = 1;
 
while (x <= 3)
{
    int y = 3;
 
    while (y >= 1)
    {
        cout << x * y << " ";
        y--;
    }
 
    x++;
}

Question 2:

Task: Predict the output.

Code

int n = 1;
int sum = 0;
 
while (n <= 3)
{
    int j = 1;
 
    while (j <= 3)
    {
        sum += n * j;
        j++;
    }
 
    n++;
}
 
cout << sum;

Question 3:

Task: Predict the output.

Code

int x = 1;
int count = 0;
 
while (x <= 5)
{
    int y = x;
 
    while (y <= 5)
    {
        count++;
        y += 2;
    }
 
    x++;
}
 
cout << count;

Question 4:

Task: Predict the output.

Code

int x = 1;
int y = 1;
 
while (x <= 4)
{
    y = 1;
 
    while (y <= x)
    {
        cout << x + y << " ";
        y++;
    }
 
    cout << endl;
    x++;
}

Question 5:

Task: Predict the output.

Code

int x = 1;
int count = 0;
 
while (x <= 4)
{
    int y = 1;
 
    while (y <= 4)
    {
        if (x + y > 4)
            count++;
 
        y++;
    }
 
    x++;
}
 
cout << count;

Question 6:

Task: Predict the output.

Code

int x = 1;
int result = 0;
 
while (x <= 4)
{
    int y = 1;
 
    while (y <= x)
    {
        result += x - y;
        y++;
    }
 
    x++;
}
 
cout << result;

Question 7:

Task: Predict the output.

Code

int x = 1;
int y = 5;
 
while (x <= 3)
{
    int z = y;
 
    while (z >= x)
    {
        cout << z << " ";
        z--;
    }
 
    cout << endl;
    x++;
    y--;
}

Practice tip: Trace each loop iteration in a small table with columns for the variables, condition, and output. Pay special attention to when variables change and when the condition is checked again.

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