C Program Structure

Program structure in programming languages refers to the basic organization and layout of code within a program.

It includes the syntax and semantics of the language, as well as conventions and best practices for writing code that is easy to read, maintain, and debug.

Creating a C program is like assembling a jigsaw puzzle where each piece contributes to the final picture. The 'pieces' in this case are the different components of the C program, all working together to create a complete, functional software. Let's embark on an architectural tour of a C program and understand how these pieces fit together.

Just like how every human being has a defined physical structure, with a head, neck, torso, and limbs, almost everything else has a structure as well. Programming languages are no exception - each one has a specific structure that must be adhered to while writing code.

In particular, the structure of a C program can be broken down into multiple parts, each with its own purpose. Following this structure can help make the program easier to read, modify, and document, as well as ensure consistency in formatting.

The structure of a C language program is the basic framework that every C program follows. The structure of a C program consists of several components or parts.

• Documentation
• Preprocessor Directives
• Header Files or Link
• Global's
• Functions Declaration
• Main function
• Functions Definition

  

/********************************************************************
    File Information:
    Filename:     	main.c
    Author:              XYZ
    Created:           DDMMYY

    Description: XYZ
********************************************************************/

#ifndef PI
    #define PI 3.14
#endif

#include <stdio.h>

int variable_x;
int variable_y;

void foo(void);

int main() {

    return 0;
}

void foo(void) {
    printf("Function Foo");    
}

Function definitions provide the actual code for the functions used in the program. They are usually placed after the main function.

  


void foo(void) {
    printf("Function Foo");    
}

Function declarations provide information about the functions used in the program, such as the name of the function, the return type, and the parameters.

  

void foo(void);

The main function is the starting point of every C program. It is the first function that gets executed when the program is run.

  

int main() {

    return 0;
}

The header files or link libraries contain function prototypes and other declarations that are required by the program.

   //include file
   #include <stdio.h>
   
   
   

Global variables are variables that are declared outside of any function, and they can be accessed from any function in the program.

  
  int variable_x;
  int variable_y;
  
  

This is the first component of the C program structure. It is used to provide information about the program, such as the name of the program, the author, the date of creation, and a brief description of what the program does.

  

/**********************************************************
    File Information:
    Filename:     	main.c
    Author:              XYZ
    Created:           DDMMYY

    Description: XYZ
**********************************************************/

In a multiple c-files program, the code is divided into multiple files, with each file containing different functions or portions of the program. This approach can help to organize large programs and make them more modular and easier to maintain.

Here's an example of a multiple C file program structure.

In this example, main.c is the entry point of the program and includes the helper.h header file, which contains the function prototype for the add() function.

File: main.c

  

#include <stdio.h>
#include "helper.h"

int main() {
  int result = add(2, 3);
  printf("Result: %d\n", result);
  return 0;
}

The actual implementation of the add() function is defined in helper.c, which also includes helper.h to ensure that the function signature matches the prototype.

File: helper.c

  

#include "helper.h"

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

File: helper.h

  

#ifndef HELPER_H
#define HELPER_H

int add(int a, int b);

#endif