বিপিএসসি নন-ক্যাডার সিএসই (বিষয়ভিত্তিক) MCQ প্রশ্ন সমাধান ২০২৫ — প্রশ্ন ও সমাধান

ব্যাখ্যা: A constructor in C++ is a special function that initializes objects. It does not return any value, not even void. (যখন একটি ক্লাসের অবজেক্ট ক্রিয়েট হয়, তখন কন্সট্রাক্টর অটো কল হয়) #include <iostream> using namespace std; class A { public: // Constructor of the class without // any parameters A() { cout << "Constructor called" << endl; } }; int main() { A obj1; return 0; } Friend function: a friend function can be granted special access to private and protected members of a class in C++. They are not the member functions of the class but can access and manipulate the private and protected members of that class for they are declared as friends. A friend function can be: ✓ A global function ✓ A member function of another class Inline Function: The whole code of the inline function is inserted or substituted at the point of its call during the compilation instead of using the normal function call mechanism. #include <iostream> using namespace std; // Inline function inline int square(int x) { return x * x; } int main() { int num = 5; // Calling inline function int res = square(num); cout << res; return 0; } Member Function: a function that is declared in a class scope.

ব্যাখ্যা: A function is said to be overloaded when it has multiple definitions with the same name but different parameters. This is known as function overloading in C++. Compile time polymorphism in which a function can perform different jobs based on the different parameters passed to it. It is a feature of object-oriented programming that increases the readability of the program. int add (int a, int b) { return a + b; } int add (int a, int b, int c) { return a + b + c; }

ব্যাখ্যা: In C++, abstract is not a modifier. Instead, an abstract class is defined by including at least one pure virtual function. The keywords private, protected, and public are valid method access modifiers. Public: Members declared as public are accessible from anywhere in the program, both inside and outside the class. This is typically used for interfaces and functions that need to be exposed to external code. Private: Members declared as private are only accessible from within the same class. They cannot be accessed directly from outside the class or by derived classes. This promotes data hiding and encapsulation, ensuring that internal implementation details are not directly manipulated by external code. By default, class members are private if no access modifier is specified. Protected: Members declared as protected are accessible within the same class and by derived classes (classes that inherit from the current class). They are not accessible directly from outside the class by non-derived classes. This allows for controlled access in inheritance hierarchies, where derived classes need to access base class members for specific functionalities.

ব্যাখ্যা: Each int takes 4 bytes. So, int array [15] will take 15 × 4 = 60 bytes.

ব্যাখ্যা: The exit () function terminates the entire program immediately, regardless of where it is called.

ব্যাখ্যা: #include <stdio.h> // Array passed as an array without the size of its // dimension void printArr(int arr[], int n) { for (int i = 0; i < n; i++) printf("%d ", arr[i]); } int main() { int arr[] = {1, 2, 3, 4, 5}; // Pass array to function printArr(arr, 5); return 0; } Explanation: In C/C++, when you pass an array to a function, it decays into a pointer, meaning the address of the first element is passed to the function. This allows the function to access and modify the original array elements directly using pointer arithmetic.

ব্যাখ্যা: A constructor is a special kind of method in object-oriented languages like C++, Java, and C#. It has the same name as the class and is used to initialize objects. Constructors are automatically called when an object is created and do not have a return type.

ব্যাখ্যা: The parentheses around *a mean that a is a pointer, not an array. The expression int (*a)[10] tells the compiler that a is a pointer to an array of 10 integers. Without parentheses, it would be int *a[10], which is an array of 10 pointers to integers.

ব্যাখ্যা: In C++, when you inherit a base class without specifying an access modifier, the inheritance is private by default. This means that public and protected members of the base class become private in the derived class unless explicitly declared otherwise. class Base { public: int x = 5; }; class Derived : Base { // equivalent to `: private Base` public: void show() { // x is private here due to private inheritance // std::cout << x; // ❌ Error } }; class → private inheritance by default struct → public inheritance by default You can override the default by explicitly specifying public, protected, or private.

ব্যাখ্যা: In C, variable names cannot contain special characters like # or -. So, No#of- students is invalid. Valid variable names can include letters, digits, and underscores, but must not start with a digit or include symbols.

ব্যাখ্যা: The break statement is used to exit a loop (for, while, do-while) or a switch block immediately, bypassing any remaining iterations or cases. It is crucial for terminating loops based on conditions checked within the loop body. #include <stdio.h> int main() { for (int i = 1; i <= 5; i++) { if (i == 3) { continue; // Skips the rest of the code for i = 3 } printf("%d\n", i); } return 0; } Output: 1 2 4 5

ব্যাখ্যা: The ASCII code for 100 corresponds to the character 'd'. Using %c in printf() prints the character associated with that ASCII value, not the number itself.

ব্যাখ্যা: A compiler translates an entire source program into machine code before execution.

ব্যাখ্যা: NOR gate outputs low when any input is high.

ব্যাখ্যা: Octal 77 + 1 = 100 in octal. (Octal 77 = Decimal 63. 63+1 = 64 = Octal 100) 77₈ = 7×8^1 + 7×8^0 = 7×8 + 7×1 = 56 + 7 = 63₁₀ 63 + 1 = 64₁₀ 64 ÷ 8 = 8 remainder 0 8 ÷ 8 = 1 remainder 0 1 ÷ 8 = 0 remainder 1 So, 64₁₀ = 100₈

ব্যাখ্যা: Bitwise OR: 10101111 | 00110011 = 10111111

ব্যাখ্যা: A flip-flop is a digital memory element used to store a single bit (0 or 1). It is the fundamental building block of memory systems, used in registers and RAM.

ব্যাখ্যা: 10000000 → MSB is 1 → So it’s a negative number. In 8-bit 2's complement representation: Step-by-step: Start with 10000000 Invert all bits: 01111111 Add 1: 01111111 + 1 = 10000000 So, the positive equivalent is 128 Therefore, the original number is: -128 10000000 = -128 The range for 8-bit signed numbers is –128 to 127.

ব্যাখ্যা: Port 53 is used for DNS (Domain Name System) services. Must remember HTTP, FTP, SMTP, telnet etc

ব্যাখ্যা: ICANN (Internet Corporation for Assigned Names and Numbers) manages the domain name system.