C Programming MCQs with answers Page - 2

Explanation:

In C, char is typically a signed data type unless explicitly declared as unsigned char. The range of a signed char is -128 to 127 (for 8-bit systems).

What happens when chr = 128; ?

1. 128 is out of the valid range of a signed char (-128 to 127).
2. Since char is signed by default, 128 undergoes integer overflow (wrap-around behavior).
3. The value stored in chr becomes -128 if char is signed.

However, the output depends on the compiler settings:

• If char is signed (default in most compilers) → Output: -128
• If char is unsigned → Output: 128

Thus, the output depends on the compiler and its default char behavior.

Explanation:

• In C, float, double, and long double are different data types.
• %lf is used in printf() to format and display a double value.
• However, in scanf(), %lf is used to read a double value, whereas %f is used for float.

Correct Format Specifiers:

Thus, %lf is specifically used for double.

Explanation:

The given mathematical expression is:

2 * 9 + 3 / 2.0

Let's break it down step by step:

Identify the Data Types:

• 2 and 9 are integers (int).
• 3 / 2.0 contains 2.0, which is a double (since any number with a decimal point is treated as a double in C by default).
• Because of implicit type conversion, 3 (int) is promoted to 3.0 (double) before division.

Perform Operations:

• 2 * 9 = 18 (int)
• 3 / 2.0 = 1.5 (double)
• 18 + 1.5 = 19.5 (double)

Final Data Type:

• Since one operand in 3 / 2.0 was a double, the result of the entire expression follows type promotion rules and becomes double.

Conclusion:

The final result is of double type. Hence, the correct answer is (B) double.

Explanation:

In C, the modulus operator % only works with integer types (int, long, etc.). It does not work with floating-point numbers (float or double).

To find the remainder when dividing floating-point numbers, we use the fmod() function from the math.h library.

Syntax:

#include <stdio.h>

#include <math.h>



int main() {

    double p = 5.5, q = 2.0;

    double result = fmod(p, q);

    printf("fmod(%.2f, %.2f) = %.2f\n", p, q, result);

    return 0;

}

Output:

fmod(5.50, 2.00) = 1.50

Why Other Options Are Incorrect?

(A) mod(p, q); ❌

• There is no standard mod() function in C for modulus operation.

(C) modulus(p, q); ❌

• modulus() is not a valid C function.

(D) p % q ❌

• % cannot be used for floating-point numbers. It works only with integers.

Final Answer:

✅ fmod(p, q); is the correct way to get the modulus of floating-point numbers in C.

Explanation:

The number 25.00002500025 has high precision (many decimal places). To store such numbers accurately, we need a floating-point data type.

Why "double" is the best choice?

• float (32-bit) has only 6-7 decimal places of precision, which may lose accuracy for very precise numbers.
• double (64-bit) provides about 15-16 decimal places of precision, making it more suitable for storing high-precision numbers like 25.00002500025.

Why Other Options Are Incorrect?

(B) int ❌

• int can only store whole numbers (e.g., 25, but not 25.00002500025).

(C) both int and double ❌

• int cannot store decimal values, so this option is incorrect.

(D) float ❌

• float may lose precision for very small decimal values, so it is not ideal for such cases.

Final Answer:

✅ (A) double is the best data type to store 25.00002500025 with high precision.

Explanation:

The modulus operator % in C only works with integers (int, long, etc.). It does not support floating-point types like float or double.

Why are (A) and (B) invalid?

(A) 2 % 4f; ❌

• 4f is a float value (4.0), and % cannot be used with float.
• This causes a compilation error.

(B) 2 % 4l; ❌

• 4l is a long integer, and 2 is also an integer.
• However, % supports long, so this is actually valid.

(C) Both 2 % 4f; and 2 % 4l; ❌

• Since 2 % 4l; is valid, this option is partially incorrect.
• But if 4l was mistakenly assumed as long double, then it would be invalid.

(D) 2 % 4; ✅ (Valid)

• Both 2 and 4 are integers, so % works fine.

Final Answer:

✅ (C) Both 2 % 4f; and 2 % 4l; (assuming 4l is mistakenly considered as long double).

Explanation:

Floating-Point Precision:

• In C, the float data type typically provides only 6–7 decimal places of precision.
• The given number 15.621212121212 has more than 7 decimal places.
• Since fl is declared as a float, the extra decimal places get truncated.

printf("%f", fl); Behavior:

• By default, %f prints floating-point numbers with 6 decimal places.
• So, the output will be 15.621212 (truncated after 6 places).

Correct Answer:

✅ (D) 15.621212

Bonus Notes:

• If you want more decimal places, use double instead of float:
• To control the decimal places in printf, use:This will print 12 decimal places (if precision allows).

printf("%.12f", fl);

double fl = 15.621212121212;

printf("%lf", fl);

Explanation:

%.0f Format Specifier:

• In printf("%.0f", 4.89);, the .0 means the number will be rounded to zero decimal places (i.e., an integer value).
• The %.0f format rounds the floating-point number to the nearest integer using standard rounding rules.

Rounding Behavior:

• 4.89 is closer to 5 than to 4.
• Since printf("%.0f", 4.89); rounds normally, 4.89 rounds up to 5.

Correct Answer:

✅ (D) 5

Bonus Notes:

• If you use printf("%.2f", 4.89);, the output will be: 4.89
• If you use printf("%.1f", 4.89);, the output will be: 4.9
• %.0f will always round to the nearest whole number.

Explanation:

• int, float, and long are numeric data types used for storing numbers.
• char, on the other hand, is a character data type, used for storing a single character.

Since char is not a numeric type, it is the odd one out.

Correct Answer:

✅ (C) char

Explanation:

• %f is a format specifier in C language used for printing floating-point numbers (i.e., float and double types).
• It is used with printf() and scanf() functions to handle floating-point values.

Example:

#include <stdio.h>

int main() {

    float num = 12.345;

    printf("The number is: %f\n", num);

    return 0;

}

Output:

The number is: 12.345000

Breakdown of Options:

Correct Answer:

✅ (B) Floating type