C program to print binary representation of number

#include<stdio.h>
#include<math.h>
//function to print binary number of a decimal
void binary(int i)
{
 if(i!=0)
  {
   binary(i>>1);
  }
 printf("%c",i&1==1?'1':'0');
}
void main()
{
 int i,k,l,j=0;
 printf("\nEnter a no");
 scanf("%d",&i);
 l=i;
 //To print binary equivalent
 printf("\nBinary representation of the no is ");
 binary(l);
}

output
Enter a no 54
Binary representation of the no is 110110

C program to sort list of names

#include<stdio.h>
#include<string.h>
void main()
{
 int i,j;
//list of names to be sort, you can customize to take input from keyboard
 char *list[]={"aj","su","punit","pushp"},*s;
printf("Input List is :")
 for(i=0;i<4;i++)
 {
  printf("\n%s ",*(list+i));
 }
 for(i=0;i<4;i++)
  {
   for(j=0;j<4-i-1;j++)
    {
     if(strcmp(*(list+j),*(list+j+1))>0)
      {
       s=*(list+j);
       *(list+j)=*(list+j+1);
       *(list+j+1)=s;
      }
    }
   }
 printf("\nSorted List is:\t");
 for(i=0;i<4;i++)
  {
   printf(" %s",*(list+i));
  }
}

output
Input List is:
aj
su
punit
pushp
Sorted List is: aj punit pushp su

C program to make a binary tree and print the tree in inorder, preorder and postorder form

#include<stdio.h>
#include<stdlib.h>
struct node
{
 int info;
 struct node *left,*right;
}*root;
//function to create a new node in tree
node *create(struct node *ptr,int n)
 {
  struct node *curr;
  curr=(node *)malloc(sizeof(node));
  if(ptr==NULL)
   {
    curr->info=n;
    curr->left=NULL;
    curr->right=NULL;
    ptr=curr;
   }
  else
   {
    if(ptr->info>n)
     ptr->left=create(ptr->left,n);
    else
     ptr->right=create(ptr->right,n);
   }
   return ptr;
 }
void preorder(struct node *ptr)
 {
  if(ptr!=NULL)
   {
    printf(" %d",ptr->info);
    preorder(ptr->left);
    preorder(ptr->right);
   }
 }
void inorder(struct node *ptr)
{
 if(ptr!=NULL)
  {
   inorder(ptr->left);
   printf(" %d",ptr->info);
   inorder(ptr->right);
  }
}
void postorder(struct node *ptr)
 {
  if(ptr!=NULL)
   {
    postorder(ptr->left);
    postorder(ptr->right);
    printf(" %d",ptr->info);
   }
 }
void main()
{
//initially root will be null as there is no node
 root=NULL;
 int n;
 int i;
 do
  {
   printf("\n\n1.insert\n\n2.preorder.\n\n3.inorder\n\n4.postorder\n\n5.exit");
   scanf("%d",&n);
   if(n==1)
    {
     printf("Enter value to insert");
     scanf("%d",&i);
     root=create(root,i);
    }
   else if(n==2)
    {
     preorder(root);
    }
   else if(n==3)
    {
     inorder(root);
    }
   else if(n==4)
    {
     postorder(root);
    }
   }while(n!=5);
 }

output

1.insert
2.preorder
3.inorder
4.postorder
5.exit
1
Enter value to insert 4

1.insert
2.preorder
3.inorder
4.postorder
5.exit
1
Enter value to insert 3
1.insert
2.preorder
3.inorder
4.postorder
5.exit
2
3 4
1.insert
2.preorder
3.inorder
4.postorder
5.exit
5

C program to find whether given string or sentence is armstrong or not

#include<stdio.h>
#include<string.h>
#include<math.h>
void main()
{
//str1 is input string here you can input here using your choice
 char str1[50]="hey its its hey",str2[50]="",strtemp[50];
 printf("Input string is %s",str1)
 strlwr(str1);
 int s[50],l[50],c=0;
 for(int i=0;i<=strlen(str1);i++)
  {
   if(str1[i]>=97&&str1[i]<=122)
    continue;
   else
    {
     if(c==0)
      {
       s[c]=0;
       l[c]=i-1;
       c++;
      }
     else
      {
       s[c]=l[c-1]+2;
       l[c]=i-1;
       c++;
      }
    }
  }
 c=c-1;
 for(i=c;i>=0;i--)
  {
   int temp=0;
   if((i!=c))
    {
     strtemp[temp]=' ';
     temp++;
    }
   for(int j=s[i];j<=l[i];j++)
    {
     strtemp[temp]=str1[j];
     temp++;
    }
   strtemp[temp]='\0';
   strcat(str2,strtemp);
  }
 printf("%s",str2);
 if((strcmp(str1,str2)==0))
  {
   printf("\nString are armstrong");
  }
 else
  {
   printf("\nString is not armstrong");
  }
}

output
Input string is hey it's it's hey
String are armstrong

C program to find whether given string is palindrome or not

Problem Statement:- you are given a string and you need to check whether the given string is palindrome or not, if yes you need to produce output yes
Palindrome:- if the string is equal to its reverse of string then it is called palindrome numbers

#include<stdio.h>
#include<string.h>
void check(char *t)
 {
  char *i;
//strlen() is used to calculate length of the string defined in string.h
  int l=strlen(t);
  while(*t!=NULL)
   {
    *i=*t;
    i++;
    t++;
   }
   *i='\0';
   t=t-l;
   i--;
   int count=0;
   while(*t!=NULL)
    {
     if(*t!=*i)
      {
       count++;
       break;
      }
      t++;
      i--;
    }
  if((count==0)&&(*t==NULL))
   {
    printf("String is palindrome");
   }
 else
  {
   printf("String is not palindrome");
  }
}

void main()
{
 char s[20];
 printf("Enter a string");
 scanf("%s",s);
 check(s);
}

output
Enter a string
swswwsws
String is palindrome

c program to sort a given string alphabetically

Problem Statement:- you are given a string and you need to sort that string into their alphabetical order. Like in "enter" the first alphabet also comes first alphabetically so it will stay there and after that the secode 'e' must come.

#include<stdio.h>
#include<string.h>
#include<ctype.h>
void main()
{
 //random string as input
 char s[15]="enter";
 int i;
 char temp;
 printf("String entered is %s ",s);
//applying logic as bubble sort for string sorting
 for(i=0;i<strlen(s);i++)
  {
   for(int k=0;k<strlen(s)-i-1;k++)
    {
     //this  will use ASCII codes for characters
     if(s[k]>s[k+1])
     {
      temp=s[k];
      s[k]=s[k+1];
      s[k+1]=temp;
     }
    }
   }
 printf("\nString is %s",s);
}

output
String entered is  enter
String is eenrt

c program to print box using stars

Problem Statement:- print square box using stars in c, you can use nested loops to solve this problem.

#include<stdio.h>
void main()
 {
  int a,n=6,i,j,k;
  for(i=1;i<=n-2;i++)
   {
    if(i==1||i==(n-2))
     {
      for(j=1;j<=n;j++)
       printf("*");
      printf("\n");
     }
    else
     {
      printf("*");
      for(j=1;j<=n-2;j++)
       printf(" ");
      printf("*");
      printf("\n");
     }
   }
}

output
******
*        *
*        *
******