Basic data types - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an integer variable named age.

C

int [1];

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

Acount

Bnumber

Cvalue

Dage

Attempts:

3 left

💡 Hint

Common Mistakes

Using a keyword as a variable name

Forgetting the semicolon at the end

The code declares an integer variable named age using the int keyword.

2fill in blank

medium

Complete the code to declare a floating-point variable named price.

C

float [1];

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

Aamount

Bprice

Ccost

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Using an integer type instead of float

Misspelling the variable name

The code declares a floating-point variable named price using the float keyword.

3fill in blank

hard

Fix the error in the code by completing the declaration of a character variable named grade.

C

char [1];

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

Amark

Bletter

Cgrade

Dscore

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string type instead of char

Using an incorrect variable name

The code declares a character variable named grade using the char keyword.

4fill in blank

hard

Fill both blanks to declare a double variable named distance and initialize it to 100.5.

C

double [1] = [2];

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

Adistance

B100.5

CdistanceValue

D100

Attempts:

3 left

💡 Hint

Common Mistakes

Using an integer value instead of a floating-point number

Using a different variable name

The code declares a double variable named distance and initializes it with the value 100.5.

5fill in blank

hard

Fill all three blanks to declare a boolean variable named isValid, initialize it to true, and print it using printf.

C

#include <stdio.h>
#include <stdbool.h>

int main() {
    bool [1] = [2];
    printf("Is valid: %d\n", [3]);
    return 0;
}

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

AisValid

Btrue

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to include stdbool.h

Using True instead of true

Printing the variable name incorrectly

The code declares a boolean variable isValid, initializes it to true, and prints its value using printf. The %d format specifier prints the integer value of the boolean.

Practice

1. Which C data type is used to store whole numbers without decimals?

easy

A. int

B. float

C. char

D. bool

Solution

1. Step 1: Understand data types for numbers

   Whole numbers without decimals are stored using the int type in C.

2. Step 2: Identify correct type for whole numbers

   float stores decimals, char stores characters, and bool stores true/false values.

3. Final Answer:

   int -> Option A

4. Quick Check:

   Whole numbers = int [OK]

Hint: Whole numbers use int type in C [OK]

Common Mistakes:

• Confusing float with int for whole numbers
• Using char for numbers
• Thinking bool stores numbers

2. Which of the following is the correct way to declare a variable of type float in C?

easy

A. int number = 3.14;

B. char number = 3.14;

C. float number = 3.14;

D. bool number = 3.14;

Solution

1. Step 1: Check variable declaration syntax

   In C, to declare a float variable, use the keyword float followed by the variable name and value.

2. Step 2: Match type with value

   Assigning 3.14 (a decimal) to a float variable is correct. Other types like int, char, or bool cannot hold decimal values properly.

3. Final Answer:

   float number = 3.14; -> Option C

4. Quick Check:

   Decimal numbers use float type [OK]

Hint: Use float keyword for decimal numbers [OK]

Common Mistakes:

• Using int for decimal values
• Assigning decimal to char
• Using bool for numbers

3. What will be the output of this C code?

char letter = 'A';
int number = 5;
float decimal = 3.5;
printf("%c %d %.1f", letter, number, decimal);

medium

A. A 5 3

B. 65 5 3.5

C. A 5 3.50

D. A 5 3.5

Solution

1. Step 1: Understand format specifiers

   %c prints a character, %d prints an integer, and %.1f prints a float with one decimal place.

2. Step 2: Match variables to specifiers

   letter = 'A' prints 'A', number = 5 prints 5, and decimal = 3.5 prints 3.5 with one decimal.

3. Final Answer:

   A 5 3.5 -> Option D

4. Quick Check:

   Format specifiers match output [OK]

Hint: Match %c, %d, %.1f to char, int, float [OK]

Common Mistakes:

• Printing char as int (shows ASCII code)
• Ignoring decimal precision
• Confusing format specifiers

4. Identify the error in this C code snippet:

bool flag = 1;
char letter = "B";
int count = 10;

medium

A. char should use single quotes for characters

B. bool cannot be assigned 1

C. int cannot be assigned 10

D. No errors, code is correct

Solution

1. Step 1: Check bool assignment

   Assigning 1 to bool is allowed since 1 means true in C.

2. Step 2: Check char assignment

   Characters must be in single quotes ('B'), not double quotes ("B") which are for strings.

3. Final Answer:

   char should use single quotes for characters -> Option A

4. Quick Check:

   char uses single quotes [OK]

Hint: Use single quotes for char, double for strings [OK]

Common Mistakes:

• Using double quotes for char
• Thinking bool can't be 1 or 0
• Confusing int assignments

5. You want to store a student's grade as a letter (A, B, C, etc.) and whether they passed (true/false). Which data types should you use in C?

hard

A. int for grade, float for pass status

B. char for grade, bool for pass status

C. float for grade, int for pass status

D. bool for grade, char for pass status

Solution

1. Step 1: Choose type for grade letter

   Grade letters like 'A' are single characters, so char is the right type.

2. Step 2: Choose type for pass status

   Pass/fail is a true/false value, so bool fits perfectly.

3. Final Answer:

   char for grade, bool for pass status -> Option B

4. Quick Check:

   Letter = char, true/false = bool [OK]

Hint: Use char for letters, bool for true/false [OK]

Common Mistakes:

• Using int or float for letter grades
• Using char for true/false values
• Mixing data types incorrectly