assignment.txt

BEGINNER C PROGRAMMING ASSIGNMENTS

General rules (apply to all assignments)
1. Use only standard C libraries.
2. Write clean, readable code with meaningful variable names.
3. Add brief comments only where logic is not obvious.
4. Check for common errors (for example: malloc failure, file open failure).
5. Compile with warnings enabled: gcc -Wall -Wextra  <file>.c -o <program>

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A. Parameter Passing (pass by reference)
Suggested file: pass_by_reference.c

Goal
Compute the expression:
(a + b) + (c * d)
using functions that return results through pointers.

Requirements
1. In main, declare integers: a, b, c, d.
2. Create:
	- void sum(int x, int y, int *result)
	- void multiply(int x, int y, int *result)
3. sum() must store x + y in *result.
4. multiply() must store x * y in *result.
5. In main:
	- Call sum(a, b, &sum_result)
	- Call multiply(c, d, &mul_result)
	- Compute final_result = sum_result + mul_result
6. Print all intermediate and final values clearly.

Expected output format (example)
a = 2, b = 3, c = 4, d = 5
sum(a, b) = 5
multiply(c, d) = 20
final = 25

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B. Pointers (triple pointer)
Suggested file: pointers.c

Goal
Understand multi-level indirection using int*, int**, and int***.

Requirements
1. Declare an integer variable (example: int value = 42;).
2. Create:
	- int *p1 = &value;
	- int **p2 = &p1;
	- int ***p3 = &p2;
3. Print:
	- value directly
	- value through *p1
	- value through **p2
	- value through ***p3
4. Also print addresses of value, p1, p2, and p3.
5. Draw a box-and-arrow diagram on paper (or as a text diagram in comments) showing links.

Success criteria
All printed values match and equal the original integer.

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C. Arrays (dynamic 2D with malloc + pointer arithmetic)
Suggested file: array.c

Goal
Create and use a dynamic 4x4 matrix using pointer arithmetic only.

Requirements
1. Allocate memory for 16 integers using malloc.
2. Treat it as a 4x4 matrix.
3. Fill values from 1 to 16 using nested loops and pointer arithmetic:
	*(*(arr + i * 4 + j)) is NOT valid for int* arr
	Correct form for int* arr is: *(arr + i * 4 + j)
4. Print matrix in this layout:
1  2  3  4
5  6  7  8
9  10 11 12
13 14 15 16
5. Do not use arr[i][j].
6. Free allocated memory at the end.

Success criteria
Matrix is correct, pointer arithmetic is used, and memory is freed.

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D. Strings (manual case conversion)
Suggested file: string.c

Goal
Write your own case-conversion functions using ASCII math (+/- 32).

Requirements
1. Create:
	- void toLowercase(char *s)
	- void toUppercase(char *s)
2. In toLowercase:
	- If character is between 'A' and 'Z', add 32.
3. In toUppercase:
	- If character is between 'a' and 'z', subtract 32.
4. Iterate until '\0'.
5. Do not use tolower(), toupper(), or other ctype helpers.
6. In main, test using at least one mixed-case sentence.

Success criteria
Functions correctly convert alphabetic characters and leave other characters unchanged.