C Syntax

Key Syntax Components

#include <stdio.h>

int main() {
    // code here
    return 0;
}

printf("Hello!");
int x = 5;

{
    int a = 10;
    printf("%d", a);
}

🔹 C Syntax Rules

C syntax rules define how code must be written to be valid and executable. Identifiers like variable and function names must start with a letter or underscore, followed by letters, digits, or underscores. Keywords like int, if, and else have special meaning and cannot be used as variable names. Case sensitivity means age and Age are different variables. Indentation and spacing improve readability but aren't required by the compiler. Understanding these syntax rules prevents frustrating errors and helps you write clean, professional code that follows industry standards.

// 1. Case sensitive
int age = 25;    // 'age' and 'Age' are different
int Age = 30;

// 2. Semicolon required
printf("Hello World");  // Correct
// printf("Hello World")   // Error: missing semicolon

// 3. Braces for blocks
if (age > 18) {
    printf("Adult");
}

// 4. Comments
// This is a single line comment
/* This is a 
   multi-line comment */

🔹 Variable Declaration

Properly declaring variables is critical for writing C programs that compile and run correctly. Variables must be declared before use, establishing their type and name like int number; float price; char grade;. The declaration allocates memory based on the data type chosen. You can initialize variables during declaration using syntax like int age = 25;, combining declaration and assignment in one statement. Good practice includes declaring variables close to where they're used and choosing meaningful names that describe their purpose, making code more readable and maintainable.

#include <stdio.h>

int main() {
    // Variable declarations
    int number = 42;
    float price = 19.99;
    char grade = 'A';
    
    // Using variables
    printf("Number: %d\n", number);
    printf("Price: %.2f\n", price);
    printf("Grade: %c\n", grade);
    
    return 0;
}

🔹 Basic Program Template

Using a consistent program template speeds up development and ensures you include all necessary components. Start with #include <stdio.h> to include the standard input/output library, followed by the int main() function definition. Inside main, write your program logic, declare variables, and perform operations. End with return 0; to indicate successful completion. This template provides the minimum structure needed for valid C programs. Following this template consistently across all your programs builds good habits and prevents common mistakes like missing headers or forgetting the main function.

#include <stdio.h>    // Standard input/output library

int main() {          // Main function starts here
    // Your code goes here
    
    printf("Welcome to C programming!\n");
    
    return 0;         // Program ends successfully
}                     // Main function ends here