/*
@Author: Vinod Selvin
@Desc: Analog Clock source code.
*/

#// program to fill polygon using floodfill
// algorithm
#include <graphics.h>
#include <stdio.h>
 
// flood fill algorithm
void flood(int x, int y, int new_col, int old_col)
{
    // check current pixel is old_color or not
    if (getpixel(x, y) == old_col) {
 
        // put new pixel with new color
        putpixel(x, y, new_col);
 
        // recursive call for bottom pixel fill
        flood(x + 1, y, new_col, old_col);
 
        // recursive call for top pixel fill
        flood(x - 1, y, new_col, old_col);
 
        // recursive call for right pixel fill
        flood(x, y + 1, new_col, old_col);
 
        // recursive call for left pixel fill
        flood(x, y - 1, new_col, old_col);
    }
}
 
int main()
{
    int gd, gm = DETECT;
 
    // initialize graph
    initgraph(&gd, &gm, "");
 
    // rectangle coordinate
    int top, left, bottom, right;
 
    top = left = 50;
    bottom = right = 300;
 
    // rectangle for print rectangle
    rectangle(left, top, right, bottom);
 
    // filling start coordinate
    int x = 51;
    int y = 51;
 
    // new color to fill
    int newcolor = 12;
 
    // new color which you want to fill
    int oldcolor = 0;
 
    // call for fill rectangle
    flood(x, y, newcolor, oldcolor);
    getch();
 
    return 0;
}

C Language online compiler

Write, Run & Share C Language code online using OneCompiler's C online compiler for free. It's one of the robust, feature-rich online compilers for C language, running the latest C version which is C18. Getting started with the OneCompiler's C editor is really simple and pretty fast. The editor shows sample boilerplate code when you choose language as 'C' and start coding!

Read inputs from stdin

OneCompiler's C online editor supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample C program which takes name as input and print your name with hello.

#include <stdio.h>
int main()
{
    char name[50];
    printf("Enter name:");
    scanf("%s", name);
    printf("Hello %s \n" , name );
    return 0;
    
}

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
}