int mark1, mark2, mark3, mark4, mark5;

int marks[5];

int marks[5];

#include <stdio.h>

int main()
{
    int marks[5] = {75, 82, 68, 90, 85};

    printf("First mark = %dn", marks[0]);
    printf("Second mark = %dn", marks[1]);

    return 0;
}

#include <stdio.h>

int main()
{
    int marks[5] = {75, 82, 68, 90, 85};
    int i;

    for (i = 0; i < 5; i++)
    {
        printf("%dn", marks[i]);
    }

    return 0;
}

#include <stdio.h>

int main()
{
    int marks[5];
    int i;

    for (i = 0; i < 5; i++)
    {
        printf("Enter marks %d: ", i + 1);
        scanf("%d", &marks[i]);
    }

    printf("nStudent Marks:n");

    for (i = 0; i < 5; i++)
    {
        printf("%dn", marks[i]);
    }

    return 0;
}

int marks[2][3] =
{
    {70, 80, 90},
    {65, 75, 85}
};

char name[20] = "Rahul";

#include <stdio.h>

int main()
{
    char name[30];

    printf("Enter your name: ");
    scanf("%29s", name);

    printf("Hello %s", name);

    return 0;
}

#include <stdio.h>
#include <string.h>

int main()
{
    char name[] = "Computer";

    printf("Length = %zu", strlen(name));

    return 0;
}

#include <stdio.h>

void welcome()
{
    printf("Welcome to C Programming");
}

int main()
{
    welcome();

    return 0;
}

int add(int, int);

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

result = add(10, 20);

#include <stdio.h>

void display(int number)
{
    printf("Number = %d", number);
}

int main()
{
    display(50);

    return 0;
}

#include <stdio.h>

int square(int number)
{
    return number * number;
}

int main()
{
    int result;

    result = square(5);

    printf("Square = %d", result);

    return 0;
}

#include <stdio.h>

int factorial(int n)
{
    if (n <= 1)
    {
        return 1;
    }

    return n * factorial(n - 1);
}

int main()
{
    printf("Factorial = %d", factorial(5));

    return 0;
}

#include <stdio.h>

int main()
{
    int number = 10;
    int *ptr;

    ptr = &number;

    printf("Value = %dn", number);
    printf("Address = %pn", (void *)ptr);

    return 0;
}

#include <stdio.h>

int main()
{
    int number = 25;
    int *ptr = &number;

    printf("Value = %d", *ptr);

    return 0;
}

#include <stdio.h>

void changeValue(int *x)
{
    *x = 100;
}

int main()
{
    int number = 20;

    changeValue(&number);

    printf("Number = %d", number);

    return 0;
}

#include <stdio.h>

struct Student
{
    int rollNo;
    char name[30];
    float marks;
};

int main()
{
    struct Student student = {101, "Rahul", 85.5};

    printf("Roll No: %dn", student.rollNo);
    printf("Name: %sn", student.name);
    printf("Marks: %.2fn", student.marks);

    return 0;
}

student.rollNo
student.name
student.marks

printf("%d", student.rollNo);

#include <stdio.h>

struct Student
{
    int rollNo;
    char name[30];
    float marks;
};

int main()
{
    struct Student students[2] =
    {
        {101, "Rahul", 85.5},
        {102, "Amit", 78.0}
    };

    int i;

    for (i = 0; i < 2; i++)
    {
        printf("%d %s %.2fn",
               students[i].rollNo,
               students[i].name,
               students[i].marks);
    }

    return 0;
}

union Data
{
    int number;
    float value;
    char letter;
};

#include <stdio.h>

enum Day
{
    MONDAY,
    TUESDAY,
    WEDNESDAY,
    THURSDAY,
    FRIDAY
};

int main()
{
    enum Day today = WEDNESDAY;

    printf("Day number = %d", today);

    return 0;
}

FILE *fp;

fp = fopen("filename.txt", "mode");

#include <stdio.h>

int main()
{
    FILE *fp;

    fp = fopen("student.txt", "w");

    if (fp == NULL)
    {
        printf("Unable to open file.");
        return 1;
    }

    fprintf(fp, "ADCA Student Recordn");
    fprintf(fp, "Roll No: 101n");
    fprintf(fp, "Marks: 85n");

    fclose(fp);

    return 0;
}

#include <stdio.h>

int main()
{
    FILE *fp;
    int ch;

    fp = fopen("student.txt", "r");

    if (fp == NULL)
    {
        printf("Unable to open file.");
        return 1;
    }

    while ((ch = fgetc(fp)) != EOF)
    {
        putchar(ch);
    }

    fclose(fp);

    return 0;
}

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int *ptr;

    ptr = malloc(5 * sizeof(int));

    if (ptr == NULL)
    {
        printf("Memory allocation failed.");
        return 1;
    }

    ptr[0] = 10;
    ptr[1] = 20;
    ptr[2] = 30;

    printf("%d", ptr[1]);

    free(ptr);

    return 0;
}

#include <stdio.h>
#define PI 3.14159

#define MAX 100

#include <stdio.h>

int main()
{
    int numbers[5];
    int i, largest;

    printf("Enter 5 numbers:n");

    for (i = 0; i < 5; i++)
    {
        scanf("%d", &numbers[i]);
    }

    largest = numbers[0];

    for (i = 1; i < 5; i++)
    {
        if (numbers[i] > largest)
        {
            largest = numbers[i];
        }
    }

    printf("Largest number = %d", largest);

    return 0;
}

#include <stdio.h>

struct Student
{
    int rollNo;
    char name[30];
    float marks;
};

int main()
{
    struct Student s;

    printf("Enter Roll Number: ");
    scanf("%d", &s.rollNo);

    printf("Enter Name: ");
    scanf("%29s", s.name);

    printf("Enter Marks: ");
    scanf("%f", &s.marks);

    printf("n--- Student Record ---n");
    printf("Roll No: %dn", s.rollNo);
    printf("Name: %sn", s.name);
    printf("Marks: %.2fn", s.marks);

    return 0;
}

Introduction

Advanced C Programming introduces students to programming concepts that are used to create more powerful, organized, and efficient C programs. After learning variables, operators, conditions, and loops, students can now work with arrays, strings, functions, pointers, structures, unions, enumerations, and file handling.

These concepts help programmers develop programs that can manage larger amounts of data and divide complex tasks into smaller, reusable components.

1. Arrays

An array is a collection of elements of the same data type stored under one variable name.

Instead of creating separate variables:

int mark1, mark2, mark3, mark4, mark5;

we can use:

int marks[5];

The elements of an array are accessed using an index.

C array indexing starts from 0.

For an array:

int marks[5];

the indexes are:

0   1   2   3   4

2. One-Dimensional Array

A one-dimensional array stores data in a single sequence.

Example

#include <stdio.h>

int main()
{
    int marks[5] = {75, 82, 68, 90, 85};

    printf("First mark = %dn", marks[0]);
    printf("Second mark = %dn", marks[1]);

    return 0;
}

3. Using a Loop with an Array

Loops are commonly used to process array elements.

#include <stdio.h>

int main()
{
    int marks[5] = {75, 82, 68, 90, 85};
    int i;

    for (i = 0; i < 5; i++)
    {
        printf("%dn", marks[i]);
    }

    return 0;
}

Output

75
82
68
90
85

4. Taking Array Input

#include <stdio.h>

int main()
{
    int marks[5];
    int i;

    for (i = 0; i < 5; i++)
    {
        printf("Enter marks %d: ", i + 1);
        scanf("%d", &marks[i]);
    }

    printf("nStudent Marks:n");

    for (i = 0; i < 5; i++)
    {
        printf("%dn", marks[i]);
    }

    return 0;
}

5. Two-Dimensional Arrays

A two-dimensional array stores data in rows and columns.

It is useful for:

• Tables
• Matrices
• Marksheets
• Mathematical calculations

Example

int marks[2][3] =
{
    {70, 80, 90},
    {65, 75, 85}
};

This represents:

6. Strings in C

A string is a sequence of characters.

C does not have a separate built-in string data type. Strings are stored using character arrays.

Example

char name[20] = "Rahul";

A C string ends with a special null character:

''

7. Reading a String

The %s format specifier can be used to read a simple word.

#include <stdio.h>

int main()
{
    char name[30];

    printf("Enter your name: ");
    scanf("%29s", name);

    printf("Hello %s", name);

    return 0;
}

scanf("%s", ...) stops reading at whitespace, so it is not suitable for a full name containing spaces.

8. Common String Functions

The <string.h> header provides many useful string functions.

Example

#include <stdio.h>
#include <string.h>

int main()
{
    char name[] = "Computer";

    printf("Length = %zu", strlen(name));

    return 0;
}

9. Functions in C

A function is a block of code designed to perform a specific task.

Functions help make programs:

• Organized
• Reusable
• Easier to test
• Easier to maintain

Example

#include <stdio.h>

void welcome()
{
    printf("Welcome to C Programming");
}

int main()
{
    welcome();

    return 0;
}

10. Function Declaration, Definition and Call

A function generally involves three important parts.

Function Declaration

int add(int, int);

Function Definition

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

Function Call

result = add(10, 20);

11. Function with Arguments

#include <stdio.h>

void display(int number)
{
    printf("Number = %d", number);
}

int main()
{
    display(50);

    return 0;
}

Here, number is a parameter of the function.

12. Function Returning a Value

A function can return a value to the calling code.

#include <stdio.h>

int square(int number)
{
    return number * number;
}

int main()
{
    int result;

    result = square(5);

    printf("Square = %d", result);

    return 0;
}

Output

Square = 25

13. Recursion

Recursion occurs when a function calls itself.

A recursive function should have a condition that stops further calls.

Example: Factorial

#include <stdio.h>

int factorial(int n)
{
    if (n <= 1)
    {
        return 1;
    }

    return n * factorial(n - 1);
}

int main()
{
    printf("Factorial = %d", factorial(5));

    return 0;
}

Output

Factorial = 120

14. Pointers

A pointer is a variable that stores the memory address of another variable.

Example

#include <stdio.h>

int main()
{
    int number = 10;
    int *ptr;

    ptr = &number;

    printf("Value = %dn", number);
    printf("Address = %pn", (void *)ptr);

    return 0;
}

Important Operators

15. Dereferencing a Pointer

Dereferencing means accessing the value stored at the address held by a pointer.

#include <stdio.h>

int main()
{
    int number = 25;
    int *ptr = &number;

    printf("Value = %d", *ptr);

    return 0;
}

Here, *ptr accesses the value of number.

16. Pointers and Functions

Pointers can be used to allow a function to modify variables in the calling function.

Example

#include <stdio.h>

void changeValue(int *x)
{
    *x = 100;
}

int main()
{
    int number = 20;

    changeValue(&number);

    printf("Number = %d", number);

    return 0;
}

Output

Number = 100

17. Structures

A structure allows different types of data to be grouped together under one name.

For example, student information may contain:

• Roll number
• Name
• Course
• Marks

Example

#include <stdio.h>

struct Student
{
    int rollNo;
    char name[30];
    float marks;
};

int main()
{
    struct Student student = {101, "Rahul", 85.5};

    printf("Roll No: %dn", student.rollNo);
    printf("Name: %sn", student.name);
    printf("Marks: %.2fn", student.marks);

    return 0;
}

18. Accessing Structure Members

The dot (.) operator is used to access members of a structure.

student.rollNo
student.name
student.marks

Example

printf("%d", student.rollNo);

19. Array of Structures

An array of structures can store information about multiple records.

#include <stdio.h>

struct Student
{
    int rollNo;
    char name[30];
    float marks;
};

int main()
{
    struct Student students[2] =
    {
        {101, "Rahul", 85.5},
        {102, "Amit", 78.0}
    };

    int i;

    for (i = 0; i < 2; i++)
    {
        printf("%d %s %.2fn",
               students[i].rollNo,
               students[i].name,
               students[i].marks);
    }

    return 0;
}

This concept is useful for developing student management and record-management programs.

20. Union

A union is similar to a structure, but its members share the same memory location.

Example

union Data
{
    int number;
    float value;
    char letter;
};

Unlike a structure, a union generally stores only one member’s value meaningfully at a time.

Structure vs Union

21. Enumeration

An enumeration (enum) is a user-defined type containing named integer constants.

Example

#include <stdio.h>

enum Day
{
    MONDAY,
    TUESDAY,
    WEDNESDAY,
    THURSDAY,
    FRIDAY
};

int main()
{
    enum Day today = WEDNESDAY;

    printf("Day number = %d", today);

    return 0;
}

By default, the first enumerator usually has the value 0, the next 1, and so on unless values are explicitly assigned.

22. File Handling

File handling allows a C program to store and retrieve information from files.

Files can be used to store:

• Student records
• Reports
• Transactions
• Text data
• Application information

The <stdio.h> header provides functions for file operations.

23. Opening a File

The fopen() function is used to open a file.

Syntax

FILE *fp;

fp = fopen("filename.txt", "mode");

Common Modes

Opening a file in "w" mode can replace existing contents, so it should be used carefully.

24. Writing to a File

#include <stdio.h>

int main()
{
    FILE *fp;

    fp = fopen("student.txt", "w");

    if (fp == NULL)
    {
        printf("Unable to open file.");
        return 1;
    }

    fprintf(fp, "ADCA Student Recordn");
    fprintf(fp, "Roll No: 101n");
    fprintf(fp, "Marks: 85n");

    fclose(fp);

    return 0;
}

25. Reading from a File

#include <stdio.h>

int main()
{
    FILE *fp;
    int ch;

    fp = fopen("student.txt", "r");

    if (fp == NULL)
    {
        printf("Unable to open file.");
        return 1;
    }

    while ((ch = fgetc(fp)) != EOF)
    {
        putchar(ch);
    }

    fclose(fp);

    return 0;
}

26. Important File Functions

Always check whether fopen() successfully opened the file before performing file operations.

27. Dynamic Memory Allocation

Dynamic memory allocation allows programs to request memory during runtime.

Common functions are provided by <stdlib.h>:

• malloc()
• calloc()
• realloc()
• free()

Example

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int *ptr;

    ptr = malloc(5 * sizeof(int));

    if (ptr == NULL)
    {
        printf("Memory allocation failed.");
        return 1;
    }

    ptr[0] = 10;
    ptr[1] = 20;
    ptr[2] = 30;

    printf("%d", ptr[1]);

    free(ptr);

    return 0;
}

Important

Memory obtained dynamically with malloc(), calloc(), or realloc() should be released using free() when it is no longer needed.

28. Preprocessor Directives

Preprocessor directives begin with #.

Common Examples

#include <stdio.h>
#define PI 3.14159

#include

Used to include header files.

#define

Used to define macros.

Example:

#define MAX 100

29. Header Files

Header files contain declarations and information needed by programs.

Common Header Files

30. Practical Program: Find Largest Number

#include <stdio.h>

int main()
{
    int numbers[5];
    int i, largest;

    printf("Enter 5 numbers:n");

    for (i = 0; i < 5; i++)
    {
        scanf("%d", &numbers[i]);
    }

    largest = numbers[0];

    for (i = 1; i < 5; i++)
    {
        if (numbers[i] > largest)
        {
            largest = numbers[i];
        }
    }

    printf("Largest number = %d", largest);

    return 0;
}

31. Practical Program: Student Record

#include <stdio.h>

struct Student
{
    int rollNo;
    char name[30];
    float marks;
};

int main()
{
    struct Student s;

    printf("Enter Roll Number: ");
    scanf("%d", &s.rollNo);

    printf("Enter Name: ");
    scanf("%29s", s.name);

    printf("Enter Marks: ");
    scanf("%f", &s.marks);

    printf("n--- Student Record ---n");
    printf("Roll No: %dn", s.rollNo);
    printf("Name: %sn", s.name);
    printf("Marks: %.2fn", s.marks);

    return 0;
}

int mark1, mark2, mark3, mark4, mark5;

int marks[5];

int marks[5];

0   1   2   3   4

#include <stdio.h>

int main()
{
    int marks[5] = {75, 82, 68, 90, 85};

    printf("First mark = %dn", marks[0]);
    printf("Second mark = %dn", marks[1]);

    return 0;
}

#include <stdio.h>

int main()
{
    int marks[5] = {75, 82, 68, 90, 85};
    int i;

    for (i = 0; i < 5; i++)
    {
        printf("%dn", marks[i]);
    }

    return 0;
}

75
82
68
90
85

#include <stdio.h>

int main()
{
    int marks[5];
    int i;

    for (i = 0; i < 5; i++)
    {
        printf("Enter marks %d: ", i + 1);
        scanf("%d", &marks[i]);
    }

    printf("nStudent Marks:n");

    for (i = 0; i < 5; i++)
    {
        printf("%dn", marks[i]);
    }

    return 0;
}

int marks[2][3] =
{
    {70, 80, 90},
    {65, 75, 85}
};

char name[20] = "Rahul";

''

#include <stdio.h>

int main()
{
    char name[30];

    printf("Enter your name: ");
    scanf("%29s", name);

    printf("Hello %s", name);

    return 0;
}

#include <stdio.h>
#include <string.h>

int main()
{
    char name[] = "Computer";

    printf("Length = %zu", strlen(name));

    return 0;
}

#include <stdio.h>

void welcome()
{
    printf("Welcome to C Programming");
}

int main()
{
    welcome();

    return 0;
}

int add(int, int);

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

result = add(10, 20);

#include <stdio.h>

void display(int number)
{
    printf("Number = %d", number);
}

int main()
{
    display(50);

    return 0;
}

#include <stdio.h>

int square(int number)
{
    return number * number;
}

int main()
{
    int result;

    result = square(5);

    printf("Square = %d", result);

    return 0;
}

Square = 25

#include <stdio.h>

int factorial(int n)
{
    if (n <= 1)
    {
        return 1;
    }

    return n * factorial(n - 1);
}

int main()
{
    printf("Factorial = %d", factorial(5));

    return 0;
}

Factorial = 120

#include <stdio.h>

int main()
{
    int number = 10;
    int *ptr;

    ptr = &number;

    printf("Value = %dn", number);
    printf("Address = %pn", (void *)ptr);

    return 0;
}

#include <stdio.h>

int main()
{
    int number = 25;
    int *ptr = &number;

    printf("Value = %d", *ptr);

    return 0;
}

#include <stdio.h>

void changeValue(int *x)
{
    *x = 100;
}

int main()
{
    int number = 20;

    changeValue(&number);

    printf("Number = %d", number);

    return 0;
}

Number = 100

#include <stdio.h>

struct Student
{
    int rollNo;
    char name[30];
    float marks;
};

int main()
{
    struct Student student = {101, "Rahul", 85.5};

    printf("Roll No: %dn", student.rollNo);
    printf("Name: %sn", student.name);
    printf("Marks: %.2fn", student.marks);

    return 0;
}

student.rollNo
student.name
student.marks

printf("%d", student.rollNo);

#include <stdio.h>

struct Student
{
    int rollNo;
    char name[30];
    float marks;
};

int main()
{
    struct Student students[2] =
    {
        {101, "Rahul", 85.5},
        {102, "Amit", 78.0}
    };

    int i;

    for (i = 0; i < 2; i++)
    {
        printf("%d %s %.2fn",
               students[i].rollNo,
               students[i].name,
               students[i].marks);
    }

    return 0;
}

union Data
{
    int number;
    float value;
    char letter;
};

#include <stdio.h>

enum Day
{
    MONDAY,
    TUESDAY,
    WEDNESDAY,
    THURSDAY,
    FRIDAY
};

int main()
{
    enum Day today = WEDNESDAY;

    printf("Day number = %d", today);

    return 0;
}

FILE *fp;

fp = fopen("filename.txt", "mode");

#include <stdio.h>

int main()
{
    FILE *fp;

    fp = fopen("student.txt", "w");

    if (fp == NULL)
    {
        printf("Unable to open file.");
        return 1;
    }

    fprintf(fp, "ADCA Student Recordn");
    fprintf(fp, "Roll No: 101n");
    fprintf(fp, "Marks: 85n");

    fclose(fp);

    return 0;
}

#include <stdio.h>

int main()
{
    FILE *fp;
    int ch;

    fp = fopen("student.txt", "r");

    if (fp == NULL)
    {
        printf("Unable to open file.");
        return 1;
    }

    while ((ch = fgetc(fp)) != EOF)
    {
        putchar(ch);
    }

    fclose(fp);

    return 0;
}

#include <stdio.h>
#include <stdlib.h>

int main()
{
    int *ptr;

    ptr = malloc(5 * sizeof(int));

    if (ptr == NULL)
    {
        printf("Memory allocation failed.");
        return 1;
    }

    ptr[0] = 10;
    ptr[1] = 20;
    ptr[2] = 30;

    printf("%d", ptr[1]);

    free(ptr);

    return 0;
}

#include <stdio.h>
#define PI 3.14159

#define MAX 100

#include <stdio.h>

int main()
{
    int numbers[5];
    int i, largest;

    printf("Enter 5 numbers:n");

    for (i = 0; i < 5; i++)
    {
        scanf("%d", &numbers[i]);
    }

    largest = numbers[0];

    for (i = 1; i < 5; i++)
    {
        if (numbers[i] > largest)
        {
            largest = numbers[i];
        }
    }

    printf("Largest number = %d", largest);

    return 0;
}

#include <stdio.h>

struct Student
{
    int rollNo;
    char name[30];
    float marks;
};

int main()
{
    struct Student s;

    printf("Enter Roll Number: ");
    scanf("%d", &s.rollNo);

    printf("Enter Name: ");
    scanf("%29s", s.name);

    printf("Enter Marks: ");
    scanf("%f", &s.marks);

    printf("n--- Student Record ---n");
    printf("Roll No: %dn", s.rollNo);
    printf("Name: %sn", s.name);
    printf("Marks: %.2fn", s.marks);

    return 0;
}