Comprehensive Solutions Guide

1. Von Neumann Architecture

Concept: The Von Neumann architecture describes a computer architecture based on the stored-program computer concept, where instruction data and program data are stored in the same memory.

Key Components:

• CPU (Central Processing Unit): Contains ALU (Arithmetic Logic Unit) and Control Unit.
• Memory Unit: Stores both data and instructions.
• Input/Output Devices: Interface with the external world.
• Bus System: Data bus, Address bus, and Control bus for communication.

2. System vs Application Software

Feature	System Software	Application Software
Purpose	Manage system resources	Perform specific user tasks
Example	OS (Windows, Linux), Drivers	Word, Chrome, Games
Dependency	Independent	Depends on System Software

3. Control Structures (if-else vs switch)

if-else: Used for ranges of values or boolean conditions. Checks conditions sequentially.

switch-case: Used for discrete values (int, char). Jumps directly to the matching case (faster for many conditions).

// Switch Example
switch(choice) {
    case 1: printf("One"); break;
    case 2: printf("Two"); break;
    default: printf("Invalid");
}

4. C Basics & Data Types

Basic Data Types:

• int (2 or 4 bytes) - Integers
• float (4 bytes) - Decimal numbers
• char (1 byte) - Characters
• double (8 bytes) - High precision decimals

Operators: = is assignment, == is comparison. & is bitwise AND, && is logical AND.

1. Recursion Examples

Factorial:

int fact(int n) {
    if(n==0) return 1;
    return n * fact(n-1);
}

Fibonacci:

int fib(int n) {
    if(n<=1) return n;
    return fib(n-1) + fib(n-2);
}

GCD:

int gcd(int a, int b) {
    if(b==0) return a;
    return gcd(b, a%b);
}

2. Arrays & Matrices

Matrix Multiplication (3x3):

for(i=0; i<3; i++) {
    for(j=0; j<3; j++) {
        res[i][j] = 0;
        for(k=0; k<3; k++)
            res[i][j] += a[i][k] * b[k][j];
    }
}

Transpose: trans[j][i] = mat[i][j];

Linear Search: Loop through array, if arr[i] == key, return index.

3. String Operations (Manual)

Palindrome Check:

int isPalindrome(char str[]) {
    int l = 0, h = strlen(str) - 1;
    while(h > l) {
        if(str[l++] != str[h--]) return 0;
    }
    return 1;
}

String Length: while(str[i] != '\0') i++;

4. Structures

Employee Structure:

struct Employee {
    int id;
    char name[50];
    float salary;
};
// In main:
struct Employee emp[10];
// Loop to input and check salary > 50000

5. File Handling

Even/Odd Separation:

FILE *f1 = fopen("input.txt", "r");
FILE *fe = fopen("even.txt", "w");
FILE *fo = fopen("odd.txt", "w");
while(fscanf(f1, "%d", &num) != EOF) {
    if(num%2==0) fprintf(fe, "%d\n", num);
    else fprintf(fo, "%d\n", num);
}

Type 1: Employee File Processing

Problem: Read employees, filter by department & salary, sort, write to file.

Logic:

1. Define struct Employee.
2. Use fread or fscanf to load data into an array of structures.
3. Loop to filter: if(strcmp(e[i].dept, "Sales")==0 && e[i].salary > 50000).
4. Sort using Bubble Sort on the filtered array based on date.
5. Write result using fprintf.

Type 2: Student Marks Processing

Problem: Read 3 files (Physics, Chem, Maths), calculate %, grade, write result.

Logic:

1. Open all 3 input files and 1 output file.
2. Loop while all files have data.
3. sum = p + c + m; percent = sum/3.0;
4. Determine grade using if-else ladder.
5. Write to output file.

Type 4: Library Management

Problem: Issue books, calculate fine.

Logic:

1. struct Book { int id; char title[50]; int issued_flag; char date[20]; }
2. Issue Function: Check if(b.issued_flag == 0) then set to 1.
3. Fine Function: Calculate days difference. if(days > 15) fine = (days-15) * 5;

Section A: 1. Number System Conversions

Binary to Decimal: Multiply each bit by 2^n. Ex: 101 = 1*4 + 0*2 + 1*1 = 5.

Decimal to Binary: Divide by 2 and record remainders. Ex: 5/2=2(1), 2/2=1(0), 1/2=0(1) -> 101.

Hexadecimal: Base 16 (0-9, A-F). 1 Hex digit = 4 Binary bits.

Section A: 2. Differentiate Between

Compiler vs Interpreter: Compiler translates whole code (faster execution), Interpreter translates line-by-line (easier debugging).

Structure vs Union: Structure has separate memory for members, Union shares memory.

while vs do-while: while checks condition first (entry controlled), do-while executes at least once (exit controlled).

Section A: 3. Basic C Programs

Prime Number: Loop from 2 to n/2, if n%i==0 then not prime.

Armstrong: Sum of cubes of digits == number.

Fibonacci: 0, 1, 1, 2, 3... (next = prev + curr).

Section A: 4. Explain with Diagram

Block Diagram of Computer: Input Unit -> CPU (ALU + CU + Memory) -> Output Unit.

Compilation Process: Source Code -> Preprocessor -> Compiler -> Assembler -> Linker -> Executable.

Section B: Category 6: Pointers

Swap using Pointers:

void swap(int *a, int *b) {
    int temp = *a;
    *a = *b;
    *b = temp;
}

Array Access: *(arr + i) is same as arr[i].

Section B: Category 7: Command Line Arguments

Syntax: int main(int argc, char *argv[])

Sum of numbers:

int sum = 0;
for(int i=1; i

a = a + b;
b = a - b;
a = a - b;

while(temp!=0) { rem=temp%10; sum+=pow(rem,n); temp/=10; }