CS Free MCQ Bank

[ Option C ]

Typecasting is the process of explicitly converting one data type into another so that a value can be used properly in an expression or calculation. 
It allows the programmer to control how data behaves during operations, for example, converting an int to float to avoid loss of precision, or converting a float to int when only the whole number part is required.

[ Option C ]

In traditional C, all variables must be declared before any action statement inside a block. An action statement is any statement that performs some operation, such as assignment, input-output, calculations, etc. 
This means variable declarations must appear at the beginning of a block, usually right after the opening brace {.
Although modern C allows declaring variables anywhere in the program, the standard rule for basic C learning is that variables must be declared before writing any executable statements.

[ Option D ]

In C language, you can initialize any number of variables at a time in a single statement, as long as they are separated by commas. For example,
int a = 11, b = 22, c = 33, d = 44, e = 55;

[ Option C ]

In C programming, floating point data types are used to represent real numbers, numbers that have fractional parts or decimals points.

• float
• double
• long double

#include <stdio.h>
#include <float.h>
void main()
{
    printf("Suraku Academy
");
    printf("Size of float : %zu Bytes
", sizeof(float));
    printf("Size of double : %zu Bytes
", sizeof(double));
    printf("Size of long double : %zu Bytes
", sizeof(long double));
    printf("Range and Precision:
");
    printf("Float: Min : %e, Max : %e, Precision : %d Digits
",FLT_MIN, FLT_MAX, FLT_DIG);
    printf("Double: Min : %e, Max : %e, Precision : %d Digits
",DBL_MIN, DBL_MAX, DBL_DIG);
    printf("Long Double: Min : %Le, Max : %Le, Precision : %d digits
",LDBL_MIN, LDBL_MAX, LDBL_DIG);
}

Output

Suraku Academy
Size of float : 4 Bytes
Size of double : 8 Bytes
Size of long double : 16 Bytes
Range and Precision:
Float: Min : 1.175494e-38, Max : 3.402823e+38, Precision : 6 Digits
Double: Min : 2.225074e-308, Max : 1.797693e+308, Precision : 15 Digits
Long Double: Min : 3.362103e-4932, Max : 1.189731e+4932, Precision : 18 digits

• In C, the format specifier %zu is used to printing results of sizeof or variables declared as size_t type. The sizeof operator returned size_t which is an unsigned integer type.
• In C, the format specifier %e is used for prints floating point numbers (float, double, long double) in scientific (exponential) notation.

[ Option C ]

In standard C (C89/C90), there is no built-in boolean data type to store true/false values. Instead, programmers typically use integers to represent boolean values, where 0 (zero) means false and any non-zero value means true.

[ Option D ]

In C programming, when we deal with floating-point values (float or double), we use specific format specifiers inside printf() and scanf() function to write and read data respectively.

• The format specifier %f is used to read or print floating-point numbers in decimal (standard) format. This is the most common specifier for float type.
• The format specifier %e is used to read or print floating-point numbers in scientific notation (exponential form).
• The format specifier %g is used to read or print floating-point numbers in either decimal or scientific notation, whichever is more compact for the given value.

[ Option C ]

In 8-bit 2’s complement representation, the Most Significant Bit (MSB) acts as the sign bit, where 0 represents positive numbers and 1 represents negative numbers.
The range of numbers in 2’s complement is calculated as -2^n-1 to 2^n-1-1, where n is the number of bits.
For 8 bits (n=8):

• Minimum: -2^8-1 = -2⁷ = -128
• Maximum: +2^8-1 - 1 = 2⁷-1 = 128 - 1 = 127

[ Option B ]

In C, real numbers (numbers with a decimal point) are stored using floating-point types, float, double, and long double.
Whenever we write a real number like 43.14, -12.58, or 0.0010, the compiler automatically treats it as a double type unless you specify otherwise because a double has more precision compared to a float, which makes it suitable for most calculations.
If we want the number to be treated as a float, we must add the letter f at the end, like 73.18f, -89.74f.

[ Option D ]

Implicit type conversion is a process in which the compiler automatically converts one data type to another during expression evaluation whenever needed. 
This automatic conversion is also known as type promotion, because lower-ranked types are promoted to higher-ranked types like char to int, int to float to ensure consistency in operations. It happens without any explicit request from the programmer, unlike type casting (explicit type conversion), which is manually performed.

[ Option C ]

The qualifier or modifiers are the keywords used to modify or qualify the properties of data types. Four types of modifiers, they are:

1. The short Modifier.
2. The long Modifier.
3. The signed Modifier.
4. The unsigned Modifier.

Data type qualifiers help us control the range of values a variable can store. When we want a variable to hold both positive and negative values, we use the signed qualifier.
By default, most integer types are already signed, but we can also write it explicitly as signed int. 

• The qualifier unsigned allow only positive values.
• The short and long qualifier change the size (range) of the variable.
• We cannot use any qualifier with float type.
• Only long qualifier is used with double type.

[ Option D ]

All the given variable names follow the rules of C identifiers. So, all are valid variable name.

[ Option B ]

The null character in C occupies exactly 1 byte of memory, as it is a single character with ASCII value 0, and every char in C is defined to be 1 byte in size by the standard. The null character is used to mark the end of a string.

[ Option D ]

In C, primitive data types like char, int, float, double etc. are the basic types built into the language to store simple values. The enum (enumeration) is a user-defined data type. It allows the programmer to define a set of named integer constants for easier code readability.

[ Option C ]

In a 16-bit architecture, an int in C typically uses 16 bits to store its value. When numbers are stored in binary using two’s complement, the range of a signed 16-bit integer is fixed. Out of the 16 bits, one bit is used for the sign, and the remaining 15 bits store the value.
This allows the smallest value to be –2¹⁵ (-32768) and the largest value to be +2¹⁵ – 1 (+32767).

[ Option A ]

In C, a character variable is used to store a single character, such as 'A', '9', or '@'. It is declared using the char data type. Even though a character variable occupies 1 byte of memory, it can store only one character at a time. 
To store multiple characters or group of characters, we use strings, which are arrays of characters.

[ Option C ]

In a 16-bit architecture, an unsigned integer uses all 16 bits (2 bytes) to store only positive values. Because there is no sign bit, all 16 bits are used for the value itself. 
The range of unsigned data type can be calculated using the formula 0 to 2ⁿ-1, where n is number of bits. So, the range of unsigned integer is 0 to 2¹⁶-1. This gives a maximum value of 65535.

[ Option D ]

In C, when a number starts with 0, it is treated as an octal number, not decimal. Octal numbers can only have digits 0 to 7.
In the given program, the number is written as 05209. Here the digit 9 is invalid in octal. Because of this invalid digit, the compiler cannot interpret the number and will throw compilation error.

[ Option A ]

The unsigned keyword is used to modify integer data types so that they can store only non-negative values.

• The unsigned is a type qualifier (modifier) used with data types like int, char, short, and long.
• If unsigned is not mentioned, the data type is signed by default.
• The unsigned is used when only positive values are required.

[ Option B ]

In C language, a variable name can only contain letters, digits, and one special symbol underscore. Other than underscore, no any other special symbol is allowed.

[ Option D ]

In C language, each data type has a specific way of writing values. 

• A character is always written inside single quotes, such as '1'. 
• A string is written inside double quotes, like "1".
• An integer is a whole number without decimal points, such as 1.
• A floating-point value represents numbers with decimals, such as 1.0.

[ Option C ]

The scope of a variable refers to where in the program that variable can be accessed. It defines the visibility and lifetime of the variable within different parts of the program, such as inside a function, within a block, or globally.

[ Option B ]

In C, implicit type conversion (type promotion) happens when two different data types are used in an expression.
C follows a fixed hierarchy to avoid loss of data, promoting lower-rank types to higher-rank types. The general promotion order is, int → unsigned → float → double.

[ Option D ]

The floating-point numbers are numbers that contain a decimal point, such as 21.5, 9.14, etc. To store such numbers, C provides floating point data types.  The keyword float and double are representing floating point numbers.