Basic data types - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of integer and float operations

What is the output of this C code snippet?

C

#include <stdio.h>
int main() {
    int a = 5;
    float b = 2.0;
    printf("%f", a / b);
    return 0;
}

A 2

B 2.000000

C 2.500000

D 0.000000

💡 Hint

Remember that dividing an int by a float results in a float.

The integer 'a' is promoted to float during division, so 5 / 2.0 equals 2.5, printed as 2.500000.

❓ Predict Output

intermediate

Size of data types

What will this program print?

C

#include <stdio.h>
int main() {
    printf("%zu", sizeof(char) + sizeof(int));
    return 0;
}

A 4

B 6

C 8

D 5

💡 Hint

On most systems, char is 1 byte and int is 4 bytes.

sizeof(char) is 1 byte, sizeof(int) is usually 4 bytes, so total is 5 bytes. But on 64-bit systems, int is 4 bytes, so sum is 5 bytes. However, the output is 5, not 8. This means option D is incorrect. We must check carefully.

❓ Predict Output

advanced

Unsigned integer overflow behavior

What is the output of this code?

C

#include <stdio.h>
int main() {
    unsigned int x = 0;
    x = x - 1;
    printf("%u", x);
    return 0;
}

A Compilation error

B 4294967295

C -1

D 0

💡 Hint

Unsigned integers wrap around on underflow.

Subtracting 1 from 0 in unsigned int wraps to the maximum unsigned int value, which is 4294967295 on 32-bit systems.

❓ Predict Output

advanced

Character and integer conversion

What does this program print?

C

#include <stdio.h>
int main() {
    char c = 'A';
    int i = c + 1;
    printf("%c %d", i, i);
    return 0;
}

A B 66

B A 65

C C 67

D Compilation error

💡 Hint

Characters are stored as numbers internally.

'A' has ASCII code 65, adding 1 gives 66 which is 'B'. So it prints 'B 66'.

🧠 Conceptual

expert

Behavior of signed integer overflow

What happens when a signed int variable in C overflows?

A It causes undefined behavior according to the C standard.

B It clamps to the maximum or minimum int value.

C It wraps around like unsigned int, producing a defined value.

D It triggers a runtime error automatically.

💡 Hint

Signed integer overflow is not defined by the C standard.

Signed integer overflow in C is undefined behavior, meaning the program may behave unpredictably.