// C Implementation for Boundary Filling Algorithm 
#include <graphics.h> 

// Function for 4 connected Pixels 
void boundaryFill4(int x, int y, int fill_color,int boundary_color) 
{ 
	if(getpixel(x, y) != boundary_color && 
	getpixel(x, y) != fill_color) 
	{ 
		putpixel(x, y, fill_color); 
		boundaryFill4(x + 1, y, fill_color, boundary_color); 
		boundaryFill4(x, y + 1, fill_color, boundary_color); 
		boundaryFill4(x - 1, y, fill_color, boundary_color); 
		boundaryFill4(x, y - 1, fill_color, boundary_color); 
	} 
} 

//driver code 
int main() 
{ 
	// gm is Graphics mode which is 
	// a computer display mode that 
	// generates image using pixels. 
	// DETECT is a macro defined in 
	// "graphics.h" header file 
	int gd = DETECT, gm; 

	// initgraph initializes the 
	// graphics system by loading a 
	// graphics driver from disk 
	initgraph(&gd, &gm, ""); 

	int x = 250, y = 200, radius = 50; 

	// circle function 
	circle(x, y, radius); 

	// Function calling 
	boundaryFill4(x, y, 6, 15); 

	delay(10000); 

	getch(); 

	// closegraph function closes the 
	// graphics mode and deallocates 
	// all memory allocated by 
	// graphics system . 
	closegraph(); 

	return 0; 
}

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Read inputs from stdin

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#include <stdio.h>
int main()
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    printf("Enter name:");
    scanf("%s", name);
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    return 0;
    
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About C

C language is one of the most popular general-purpose programming language developed by Dennis Ritchie at Bell laboratories for UNIX operating system. The initial release of C Language was in the year 1972. Most of the desktop operating systems are written in C Language.

Key features:

  • Structured Programming
  • Popular system programming language
  • UNIX, MySQL and Oracle are completely written in C.
  • Supports variety of platforms
  • Efficient and also handle low-level activities.
  • As fast as assembly language and hence used as system development language.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition if-else is used.

if(conditional-expression) {
   // code
} else {
   // code
}

You can also use if-else for nested Ifs and if-else-if ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to if-else-if ladder.

switch(conditional-expression) {    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
...    
    
default:     
 // code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  // code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while(condition) {  
 // code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {
  // code 
} while (condition);

Arrays

Array is a collection of similar data which is stored in continuous memory addresses. Array values can be fetched using index. Index starts from 0 to size-1.

Syntax

One dimentional Array:

data-type array-name[size];

Two dimensional array:

data-type array-name[size][size];

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity.

Two types of functions are present in C

  1. Library Functions:

Library functions are the in-built functions which are declared in header files like printf(),scanf(),puts(),gets() etc.,

  1. User defined functions:

User defined functions are the ones which are written by the programmer based on the requirement.

How to declare a Function

return_type function_name(parameters);

How to call a Function

function_name (parameters)

How to define a Function

return_type function_name(parameters) {  
  //code
}