#include <stdio.h>
#include<conio.h>
int main()
{
    printf("Hello World!");
}
#include <conio.h>
#include <dos.h>
#include <graphics.h>
#include <stdio.h>
void main()
{
	int gr = DETECT, gm;
	int r, c, x = 30, y = 30, black = 0;
	initgraph(&gr, &gm, "C:\\TURBOC3\\BGI");
	for (r = 0; r < 8; r++) {
		for (c = 1; c <= 8; c++) {
			if (black == 0) {
				setcolor(WHITE);
				setfillstyle(SOLID_FILL, BLACK);

				// creating rectangle
				// with length and breadth
				// with size 30
				rectangle(x, y, x + 30, y + 30);

				// Fill an enclosed area
				floodfill(x + 1, y + 1, WHITE);

				// Set black to true
				black = 1;
			}

			// If current block is to
			// color as white
			else {
				setcolor(WHITE);

				// sets the current fill
				// pattern and fill color
				// for whitw boxes
				setfillstyle(SOLID_FILL, WHITE);

				// creating rectangle
				// with length and breadth
				// with size 30
				rectangle(x, y, x + 30, y + 30);

				// Fill an enclosed area
				floodfill(x + 1, y + 1, WHITE);

				// Set black to false
				black = 0;
			}
			x = x + 30;
			delay(30);
		}
		if (black == 0)
			black = 1;
		else
			black = 0;

		delay(30);
		x = 30;
		y = 30 + y;
	}

	
	getch();
	closegraph();
}
by

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
}