Basic formatting in C++ - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print a formatted integer using cout.

C++

#include <iostream>
int main() {
    int number = 42;
    std::cout << [1] << std::endl;
    return 0;
}

Drag options to blanks, or click blank then click option'

A"number"

Bstd::endl

Cnumber

D42

Attempts:

3 left

💡 Hint

Common Mistakes

Putting quotes around the variable name, which prints the word instead of the value.

Using std::endl instead of the variable.

The variable number holds the integer value to print. Using std::cout << number outputs its value.

2fill in blank

medium

Complete the code to print a floating-point number with two decimal places using std::fixed and std::setprecision.

C++

#include <iostream>
#include <iomanip>
int main() {
    double pi = 3.14159;
    std::cout << std::fixed << std::setprecision([1]) << pi << std::endl;
    return 0;
}

Drag options to blanks, or click blank then click option'

A3

B0

C1

D2

Attempts:

3 left

💡 Hint

Common Mistakes

Using setprecision without std::fixed, which changes total digits instead of decimal places.

Choosing the wrong number for precision.

Using std::setprecision(2) with std::fixed formats the floating-point number to show two digits after the decimal point.

3fill in blank

hard

Fix the error in the code to print a string and an integer separated by a space.

C++

#include <iostream>
#include <string>
int main() {
    std::string name = "Alice";
    int age = 30;
    std::cout << name [1] " " << age << std::endl;
    return 0;
}

Drag options to blanks, or click blank then click option'

A,

B<<

C+

D>>

Attempts:

3 left

💡 Hint

Common Mistakes

Using + which tries to add strings and integers causing errors.

Using , which is not valid syntax for cout.

In C++, to print multiple items with std::cout, use the insertion operator << between each item.

4fill in blank

hard

Fill both blanks to create a formatted output that prints a number with a width of 5 and fills empty spaces with zeros.

C++

#include <iostream>
#include <iomanip>
int main() {
    int num = 7;
    std::cout << std::setw([1]) << std::setfill([2]) << num << std::endl;
    return 0;
}

Drag options to blanks, or click blank then click option'

A5

B'0'

C10

D' '

Attempts:

3 left

💡 Hint

Common Mistakes

Using a space character for fill instead of zero.

Setting width to a number other than 5.

std::setw(5) sets the width to 5 characters, and std::setfill('0') fills empty spaces with zeros.

5fill in blank

hard

Fill all three blanks to print a floating-point number with width 8, precision 3, and left alignment.

C++

#include <iostream>
#include <iomanip>
int main() {
    double value = 12.34567;
    std::cout << std::[1] << std::setw([2]) << std::setprecision([3]) << value << std::endl;
    return 0;
}

Drag options to blanks, or click blank then click option'

Aleft

B8

C3

Dright

Attempts:

3 left

💡 Hint

Common Mistakes

Using right alignment instead of left.

Mixing up width and precision values.

std::left aligns output to the left, std::setw(8) sets width to 8, and std::setprecision(3) sets decimal precision to 3.