#include<stdio.h>
#include<stdlib.h>
#define MAX 5
char CQ[MAX];
int f = -1, r = -1;
void CQinsert(char elem)

{
if (CQfull())
printf("\n\n Overflow!!!!\n\n");
else
{
if (f == -1)
f = 0;
r = (r + 1) % MAX;
CQ[r] = elem;
}
}
int CQdelete()
{
char elem;
if (CQempty())
{
printf("\n\nUnderflow!!!!\n\n");
return (-1);
}
else
{
elem = CQ[f];
if (f == r)
{
f = -1;
r = -1;
}
else
f = (f + 1) % MAX;
return (elem);
}
}

int CQfull()
{
if ((f == r + 1) || (f == 0 && r == MAX - 1))
return 1;
return 0;
}
int CQempty()
{
if (f == -1)
return 1;
return 0;
}
void display()
{
int i;
if (CQempty())
printf(" \n Empty Queue\n");
else
{
printf("Front[%d]->", f);
for (i = f; i != r; i = (i + 1) % MAX)
printf("%c ", CQ[i]);
printf("%c ", CQ[i]);
printf("<-[%d]Rear", r);
}
}
int main()
{
int opn;
char elem,ch;
while(1)
{
printf("Enter your choice :\n 1:Insert\n2:Delete\n3:Display\n4:Exit\nChoose anoption ");
scanf("%d", &opn);
ch=getchar();
switch(opn)
{
case 1:printf("\nEnter the element to be Inserted:");
scanf("%c", &elem);
ch=getchar();
CQinsert(elem);
break;
case 2:elem = CQdelete();
if (elem != -1)
printf("\n\nDeleted Element is %c \n", elem);
break;
case 3:printf("\n\nThe Circular Queue is\n");
display();
break;
case 4:exit(0);
}
} 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
}