Unit 1: Basics, Algorithm & Operators ( Programming in C Language)

1️⃣ Explain Algorithm with Example and Properties.

Definition:
Algorithm is a step-by-step procedure to solve a problem in a finite number of steps.

Example: Add two numbers

1. Start

2. Read two numbers, A and B

3. Calculate Sum = A + B

4. Print Sum

5. Stop

Properties of a good algorithm:

• Input: Accepts zero or more inputs

• Output: Produces at least one output

• Definiteness: Steps are clear and unambiguous

• Finiteness: Algorithm must terminate after finite steps

• Effectiveness: Steps are basic, feasible, and solvable manually or by machine

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2️⃣ Draw Flowchart and Explain Sum of First 10 Numbers

Flowchart:

   ┌───────┐
   │ Start │
   └───┬───┘
       ↓
   i=1, sum=0
       ↓
 ┌── i ≤ 10 ? ──┐
 │ Yes        No│
 ↓             ↓
sum=sum+i     Print sum
i=i+1         ↓
 │          ┌───────┐
 └─────────► Stop  │
             └─────┘

Explanation:

• Initialize i=1 and sum=0.

• Check condition i ≤ 10.

• Add i to sum and increment i.

• Repeat until i > 10.

• Print final sum and stop.

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3️⃣ Explain Compilation & Execution Process in C

Steps:

1. Editing: Write source code in .c file.

2. Preprocessing: Removes comments, expands macros, includes header files.

3. Compilation: Converts source code to assembly code.

4. Assembly: Converts assembly code into object code (.o file).

5. Linking: Combines object code with libraries to produce executable.

6. Execution: OS loads and runs the executable file.

Example:

#include <stdio.h>
int main() {
    printf("Hello, World!");
    return 0;
}

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4️⃣ Explain Keywords, Identifiers, and Constants in C

Keywords: Reserved words in C with predefined meaning.
Example: int, float, if, else, return

Identifiers: User-defined names for variables, functions, arrays, etc.
Example: sum, age, myFunction

Constants: Fixed values that do not change.
Example: #define PI 3.14 or const int x = 5;

Difference between Keywords and Identifiers:

Keywords	Identifiers
Reserved by C	User-defined names
Cannot be used as variable names	Can be used as variable or function names
Example: int, float	Example: sum, age

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5️⃣ Explain Operators in C with Examples

Types of operators:

1. Arithmetic: + - * / %

2. Unary: ++ --

3. Relational/Logical: > < == != && || !

4. Bitwise: & | ^ << >>

5. Assignment: = += -= *= /= %=

6. Conditional: ?:

Examples:

int a=5, b=3;
int c;
c = a + b;  // 8
c = a & b;  // 1 (bitwise AND)
c = a << 1; // 10 (left shift)

Precedence & Associativity:

• Precedence decides which operator evaluated first

• Associativity decides order for operators with same precedence

Example:

10 + 20 * 5  // 110, '*' has higher precedence
100 / 10 * 5 // 50, '/' and '*' have same precedence, left-to-right

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Unit 2: Control Structures, Functions, Arrays

6️⃣ Explain Control Structures in C with Examples

Definition: Control structures manage the flow of execution in a program.

Types:

1. Sequential: Statements executed line by line.

2. Decision Making (Selection): if, if-else, switch-case

3. Loops (Iteration): for, while, do-while

4. Jump Statements: break, continue, goto

Examples:

For Loop (Factorial):

int n=5, i, fact=1;
for(i=1;i<=n;i++) fact*=i;
printf("%d", fact);

While Loop (Even Numbers):

int i=2;
while(i<=10){ printf("%d ",i); i+=2; }

Switch-Case:

int day=3;
switch(day){
  case 1: printf("Mon"); break;
  case 2: printf("Tue"); break;
  default: printf("Other"); 
}

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7️⃣ Explain Functions in C with Types and Examples

Definition: Block of code that performs a specific task and can be reused.

Advantages: Code reusability, easy debugging, modularity

Types:

• Library functions: printf(), scanf()

• User-defined functions

Categories based on arguments & return type:

1. No arguments, no return:

void hello(){ printf("Hi"); }

2. Arguments, no return:

void sum(int a,int b){ printf("%d",a+b); }

3. No arguments, return value:

int getNum(){ return 10; }

4. Arguments & return:

int add(int a,int b){ return a+b; }

Call by value vs Call by reference:

• Call by value → function gets a copy, original variable not changed

• Call by reference → function gets address, original variable can be changed

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8️⃣ Explain Arrays in C with Examples

Definition: Array = collection of elements of same type in contiguous memory.

Types:

• 1D Array: int arr[5]={1,2,3,4,5};

• 2D Array: int mat[2][2]={{1,2},{3,4}};

• Multidimensional Array

Example Programs:

Sum of 1D Array:

int arr[5], i, sum=0;
for(i=0;i<5;i++){ scanf("%d",&arr[i]); sum+=arr[i]; }
printf("Sum=%d", sum);

Matrix Addition (2D Array):

int a[2][2], b[2][2], sum[2][2], i,j;
for(i=0;i<2;i++) for(j=0;j<2;j++) scanf("%d",&a[i][j]);
for(i=0;i<2;i++) for(j=0;j<2;j++) scanf("%d",&b[i][j]);
for(i=0;i<2;i++) for(j=0;j<2;j++) sum[i][j]=a[i][j]+b[i][j];
for(i=0;i<2;i++){ for(j=0;j<2;j++) printf("%d ",sum[i][j]); printf("\n"); }

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9️⃣ Program Based Long Questions

1. Factorial using recursion:

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

2. Sum of first 10 numbers using loop & function:

int sum10(){ int i, sum=0; for(i=1;i<=10;i++) sum+=i; return sum; }

3. Matrix addition program → See 2D array example above.

4. Demonstrate Bitwise Operators:

int a=5,b=3;
printf("%d %d %d %d %d", a&b, a|b, a^b, a<<1, a>>1);