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tamilvanan
tamilvanan

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Learn C - 001

#c #programming #coding #learning

Note: I’m not an expert. I’m writing this blog just to document my learning journey. 🚀

Let’s build up your understanding of the C programming language from the ground up. C is a powerful and foundational language, often considered the "mother of all modern languages" because many other languages (like C++, Java, and even Python) are influenced by it.

🔰 1. What Is C?

C is a general-purpose, procedural, and low-level programming language developed in the early 1970s by Dennis Ritchie at Bell Labs. It was originally created to implement the UNIX operating system.

Why Learn C?

  • It's fast and gives you low-level memory access.
  • It teaches you how computers actually work.
  • It's used in operating systems, embedded systems, compilers, drivers, and more.

🧱 2. Basics of a C Program

Here’s a simple C program:

#include <stdio.h>

int main() {
    printf("Hello, world!\n");
    return 0;
}
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Breakdown:

  • #include <stdio.h> – Includes the Standard Input Output library.
  • int main() – Entry point of the program.
  • printf() – Function to print text.
  • return 0; – Indicates successful program termination.

🧠 3. Key Concepts

📌 Variables & Data Types

Variables store data. C is statically typed, so you must declare types.

int age = 25;
float weight = 70.5;
char grade = 'A';
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📌 Operators

  • Arithmetic: +, -, *, /, %
  • Comparison: ==, !=, >, <, >=, <=
  • Logical: &&, ||, !

📌 Control Flow

if, else, else if 

if (age > 18) {
    printf("Adult\n");
} else {
    printf("Minor\n");
}
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for, while, do-while 

for (int i = 0; i < 5; i++) {
    printf("%d\n", i);
}
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🔄 4. Functions

Functions allow code reuse.

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

int main() {
    int result = add(3, 4);
    printf("Sum is %d\n", result);
}
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🧱 5. Arrays and Strings

Arrays 

int numbers[5] = {1, 2, 3, 4, 5};
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Strings (character arrays) 

char name[] = "Alice";
printf("%s", name);
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📦 6. Pointers

Pointers store memory addresses.

int x = 10;
int *p = &x;
printf("%d", *p);  // Outputs 10
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Understanding pointers is key in C, especially for arrays, functions, and memory management.

🗃️ 7. Structures

Used to group variables of different types.

struct Person {
    char name[50];
    int age;
};

struct Person p1 = {"Alice", 30};
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🔧 8. Memory Management

Manual memory handling using:

  • malloc() – allocate memory
  • free() – deallocate memory 
int *ptr = malloc(sizeof(int) * 5);
free(ptr);
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🧰 9. File Handling

C supports file operations:

FILE *f = fopen("data.txt", "r");
fscanf(f, "%s", buffer);
fclose(f);
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🧪 10. Compilation & Execution

C is compiled using tools like GCC.

gcc program.c -o program
./program
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🔚 In Summary

Concept Description
Low-level Close to hardware
Compiled Translated before execution
Fast Excellent for performance-critical tasks
Manual memory No garbage collection
Portable Works on various systems

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