Advanced Coding & Software Engineering Program

Basic Syntax of C

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Last Updated on: 3rd Jul 2025 03:35:42 AM

Understanding the basic syntax is the first step toward writing correct and clean C programs. The syntax defines how statements, functions, and blocks should be written for the compiler to understand and execute the program properly.

 

1. Tokens in C

In C programming, a token is the smallest meaningful unit in the code. The compiler breaks the source code into these tokens for processing.

There are 6 types of tokens in C:

 

a. Keywords

• These are reserved words that have predefined meanings in the C language.

• You cannot use them as variable or function names.

 

Examples: int, float, if, else, while, return, break, switch

 

keyword                 perpose

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int                        Defines integer type

return                    Ends a function and returns a value

if , else                  Used for conditional logic

 

2. Structure of a C Program

Every C program follows a standard structure. Here's a simple example:

 

#include <stdio.h>      // Preprocessor directive

int main() {            // Main function starts
    // Code statements go here
    return 0;           // End of program
}

 

Breakdown of the Structure:

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Section	Description
#include <stdio.h>	Tells the compiler to include the Standard Input Output header file
int main()	Every C program starts with the main function
{ ... }	Curly braces define the body of the function
return 0;	Ends the program and returns control to the system

 

2. Basic Rules of c Syntax :

• Every statement ends with a semicolon (;).

• C is case-sensitive. (total and Total are different).

• The program starts executing from the main() function.

 

Example – Simple Program Structure

 

#include <stdio.h>

int main() {
    int number = 10;   // variable declaration
    number = number + 5;
    return 0;
}

 

Summary : 

• Tokens are the building blocks: keywords, identifiers, constants, operators, etc.

• C programs start from the main() function and are built using proper syntax rules.

• Use semicolons, follow case sensitivity, and organize your code using functions and blocks.

 

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