C program to reverse an array

#include  
int main() 
{ 
      int n, c, d, a[100], b[100]; 
      printf("Enter the number of elements in array\n"); 
      scanf("%d", &n); 
      printf("Enter the array elements\n"); 
      for (c = 0; c < n ; c++) 
           scanf("%d", &a[c]); 
      for (c = n - 1, d = 0; c >= 0; c--, d++) 
           b[d] = a[c]; 
      for (c = 0; c < n; c++) 

           a[c] = b[c]; 

      printf("Reverse array is\n"); 

      for (c = 0; c < n; c++) 

      printf("%d\n", a[c]);
 
 return 0; 

}

This program reverses the array elements. For example if a is an array of integers with three elements such that
a[0] = 1
a[1] = 2
a[2] = 3

Then on reversing the array will be
a[0] = 3
a[1] = 2
a[0] = 1

C Program to Print a pyramid string triangle

#include <stdio.h>
#include <string.h>
int main()
{
         int i,j,length;
         char arr[] = "Programming";
         length = strlen(arr);
         for (i = length; i >= 0; i--)
        {
            printf("\n");
           for (j = 0; j< i; j++)
          {
                  printf("%c",arr[j]);
          }
       }
     return 0;
}

Output:

Programming

Programmin

Programmi

Programm

Program

Progra

Progr

Prog

Pro

Pr

P

C Program to count Number of Words in a Line

#include<stdio.h>
#include<string.h>
void main()
{
        char str[20];
        char *p;
        int count=0;
        clrscr();
        printf("Enter the Line:");
        gets(str);
        p=str;

        while(*p!='\0')
        {
              if(*p=='')
              {
                       count++;
              }
              p++;
        }
        printf("The number of Word is: %d",count+1);
        getch();
}
Output:Enter the Line: C Programming Language
The number of Word is: 3

Write a C program to reverse the given number and check if the number is palindrome.

int main()
{
  int n, reverse=0, rem,temp;
  printf("Enter an integer: ");
  scanf("%d", &n);
  temp=n;
  while(temp!=0)
  {
     rem=temp%10;
     reverse=reverse*10+rem;
     temp/=10;
  }  
/* Checking if number entered by user and it's reverse number is equal. */  
  if(reverse==n)  
      printf("%d is a palindrome.",n);
  else
      printf("%d is not a palindrome.",n);
  return 0;
}
Output:
Enter an integer: 12321
12321 is a palindrome.

Write a C program to find the sum of the first 15 even numbers and calculate the square of the sum

void main()
{
     int c=1,i;
     unsigned int s=0;
     for(i=1;i<=15;i++)
     {
        if(i%2==0)
        {
            s=s+i;
            c=c+i;
        }
     }
     printf("Sum of the first 15 even numbers is: %d",s);
     printf("Square of the sum is: %d",(s*s));
}

Write a C program to find the total and average of the marks given in an array.

void main()
{
     int i;
     int Avg;
     int maks[20]; 
     clrscr();
     sum=0;
     for(i=0;i<=9;i++)
     {
           printf(" Enter Marks/n ");
           scanf("%d",&marks[i] );   
     }
     for(i=0;i<=9;i++)
     {
           sum = sum + marks[i];
           Avg = sum/10;
           printf(" Total= %d\n" , sum);
           printf(" Average Marks = %d\n" , Avg);
     }
} 

Write a C program to search the given number in an array using binary search

int main()
{

    int a[10],i,n,m,c,l,u;

    printf("Enter the size of an array: ");
    scanf("%d",&n);

    printf("Enter the elements of the array: " );
    for(i=0;i<n;i++)
    {
         scanf("%d",&a[i]);
    }

    printf("Enter the number to be search: ");
    scanf("%d",&m);

    l=0,u=n-1;
    c=binary(a,n,m,l,u);
    if(c==0)
         printf("Number is not found.");
    else
         printf("Number is found.");

    return 0;
}
int binary(int a[],int n,int m,int l,int u)
{

     int mid,c=0;

     if(l<=u)
     {
          mid=(l+u)/2;
          if(m==a[mid])
          {
              c=1;
          }
          else if(m<a[mid])
          {
              return binary(a,n,m,l,mid-1);
          }
          else
              return binary(a,n,m,mid+1,u);
     }
     else
          return c;
}
Output:
Enter the size of an array: 5
Enter the elements of the array: 8 9 10 11 12
Enter the number to be search: 8
Number is found.

Write a C program to convert the given decimal number to binary, Octal and Hexadecimal

Convert Decimal to Binary:

int main()
{
    long int decimalNumber,remainder,quotient;
    int binaryNumber[100],i=1,j;
    printf("Enter any decimal number: ");
    scanf("%ld",&decimalNumber);
    quotient = decimalNumber;
    while(quotient!=0){
         binaryNumber[i++]= quotient % 2;
         quotient = quotient / 2;
    }
    printf("Equivalent binary value of decimal number %d: ",decimalNumber);
    for(j = i -1 ;j> 0;j--)
         printf("%d",binaryNumber[j]);

    return 0;
}
output:
Enter any decimal number: 50
Equivalent binary value of decimal number 50: 110010

Convert Decimal to Octal:

int main(){
  long int decimalNumber,remainder,quotient;
  int octalNumber[100],i=1,j;

  printf("Enter any decimal number: ");
  scanf("%ld",&decimalNumber);

  quotient = decimalNumber;
  while(quotient!=0){
      octalNumber[i++]= quotient % 8;
      quotient = quotient / 8;
  }
  printf("Equivalent octal value of decimal number %d: ",decimalNumber);
  for(j = i -1 ;j> 0;j--)
      printf("%d",octalNumber[j]);
  return 0;
}
Output:
Enter any decimal number: 50
Equivalent octal value of decimal number 50: 62

2. Easy way to convert decimal number to octal number in c
#include
int main(){
  long int decimalNumber;
  printf("Enter any decimal number : ");
  scanf("%d",&decimalNumber);
  printf("Equivalent octal number is: %o",decimalNumber);
  return 0;
}
output:
Enter any decimal number: 25
Equivalent octal number is: 31

Convert Decimal to Hexadecimal:

int main(){
    long int decimalNumber,remainder,quotient;
    int i=1,j,temp;
    char hexadecimalNumber[100];

    printf("Enter any decimal number: ");
    scanf("%ld",&decimalNumber);

    quotient = decimalNumber;

    while(quotient!=0){
         temp = quotient % 16;

      //To convert integer into character
      if( temp < 10)
           temp =temp + 48;
      else
         temp = temp + 55;

      hexadecimalNumber[i++]= temp;
      quotient = quotient / 16;
  }

    printf("Equivalent hexadecimal value of decimal number %d: ",decimalNumber);
    for(j = i -1 ;j> 0;j--)
      printf("%c",hexadecimalNumber[j]);

    return 0;
}

Output:

Enter any decimal number: 45
Equivalent hexadecimal value of decimal number 45: 2D

2. Easy way to convert decimal number to hexadecimal number:

#include
int main(){

  long int decimalNumber;

  printf("Enter any decimal number: ");
  scanf("%d",&decimalNumber);

  printf("Equivalent hexadecimal number is: %X",decimalNumber);

  return 0;
}

Output:
Enter any decimal number: 45
Equivalent hexadecimal number is: 2D

Write a C program to generate a multiplication table

int main(){
  int r,i,j,k;
  printf("Enter the number range: ");
  scanf("%d",&r);
  for(i=1;i<=r;i++){
      for(j=1;j<=10;j++)
           printf("%d*%d=%d ",i,j,i*j);
      printf("\n");
  }
  return 0;
}

Output:
Enter the number range: 5

1*1=1 1*2=2 1*3=3 1*4=4 1*5=5 1*6=6 1*7=7 1*8=8 1*9=9 1*10=10

2*1=2 2*2=4 2*3=6 2*4=8 2*5=10 2*6=12 2*7=14 2*8=16 2*9=18 2*10=20
3*1=3 3*2=6 3*3=9 3*4=12 3*5=15 3*6=18 3*7=21 3*8=24 3*9=27 3*10=30
4*1=4 4*2=8 4*3=12 4*4=16 4*5=20 4*6=24 4*7=28 4*8=32 4*9=36 4*10=40
5*1=5 5*2=10 5*3=15 5*4=20 5*5=25 5*6=30 5*7=35 5*8=40 5*9=45 5*10=50

Write a C program to demonstrate passing structures to functions.

In C, structure can be passed to functions by two methods: 1) Passing by value (passing actual value as argument) 2) Passing by reference (passing address of an argument) Passing structure by value:

#include 
struct student{
    char name[50];
    int roll;
};
void Display(struct student stu);
/* function prototype should be below to the structure declaration otherwise compiler shows error */
int main(){
    struct student s1;
    printf("Enter student's name: ");
    scanf("%s",&s1.name);
    printf("Enter roll number:");
    scanf("%d",&s1.roll);
    Display(s1);   // passing structure variable s1 as argument
    return 0;
}
void Display(struct student stu){
  printf("Output\nName: %s",stu.name);
  printf("\nRoll: %d",stu.roll);
}
Output:
Enter student's name: Kevin Amla
Enter roll number: 149
Output
Name: Kevin Amla
Roll: 149

Passing structure by reference:

#include 
struct distance{
    int feet;
    float inch;
};
void Add(struct distance d1,struct distance d2, struct distance *d3); 
int main()
{
    struct distance dist1, dist2, dist3;
    printf("First distance\n");
    printf("Enter feet: ");
    scanf("%d",&dist1.feet);
    printf("Enter inch: ");
    scanf("%f",&dist1.inch);
    printf("Second distance\n");
    printf("Enter feet: ");
    scanf("%d",&dist2.feet);
    printf("Enter inch: ");
    scanf("%f",&dist2.inch);
    Add(dist1, dist2, &dist3); 

/*passing structure variables dist1 and dist2 by value whereas passing structure variable dist3 by reference */
    printf("\nSum of distances = %d\'-%.1f\"",dist3.feet, dist3.inch);
    return 0;
}
void Add(struct distance d1,struct distance d2, struct distance *d3) 
{
/* Adding distances d1 and d2 and storing it in d3 */
     d3->feet=d1.feet+d2.feet; 
     d3->inch=d1.inch+d2.inch;
     if (d3->inch>=12) {     /* if inch is greater or equal to 12, converting it to feet. */
         d3->inch-=12;
         ++d3->feet;
    }
}
Output:
First distance
Enter feet: 12
Enter inch: 6.8
Second distance
Enter feet: 5
Enter inch: 7.5

Sum of distances = 18'-2.3"

How to swap two numbers in c without using third variable

#include
int main(){

    int a=5,b=10;

    //process one
    a=b+a;
    b=a-b;
    a=a-b;
    printf("a= %d  b=  %d",a,b);

    //process two
    a=5;b=10;
    a=a+b-(b=a);
    printf("\na= %d  b=  %d",a,b);

    //process three
    a=5;b=10;
    a=a^b;
    b=a^b;
    a=b^a;
    printf("\na= %d  b=  %d",a,b);

    //process four
    a=5;b=10;
    a=b-~a-1;
    b=a+~b+1;
    a=a+~b+1;
    printf("\na= %d  b=  %d",a,b);

    //process five
    a=5,b=10;
    a=b+a,b=a-b,a=a-b;
    printf("\na= %d  b=  %d",a,b);

    return 0;
}

Wrie a C program to print Pascal triangle using for loop

long fact(int);
int main()
{
    int line,i,j;

    printf("Enter the no. of lines: ");
    scanf("%d",&line);

    for(i=0;i<line;i++){
         for(j=0;j<line-i-1;j++)
             printf(" ");

         for(j=0;j<=i;j++)
             printf("%ld ",fact(i)/(fact(j)*fact(i-j)));
         printf("\n");
    }
    return 0;
}
long fact(int num)
{
    long f=1;
    int i=1;
    while(i<=num)
    {
         f=f*i;
         i++;
    }
  return f;
}
Output:
Enter the no. of lines: 8
        1
      1  1
    1  2  1
  1  3  3  1
1  4  6  4  1

Check given number is prime number or not using c program

Definition of prime number: A natural number greater than one has not any other divisors except 1 and itself. In other word we can say which has only two divisors 1 and number itself. 

For example: 5 Their divisors are 1 and 5. 
Note: 2 is only even prime number. 

Logic for prime number in c: We will take a loop and divide number from 2 to number/2. If the number is not divisible by any of the numbers then we will print it as prime number. 

 Example of prime numbers: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199 etc. 

 Find given number is prime or not:

int main(){

    int num,i,count=0;
    printf("Enter a number: ");
    scanf("%d",&num);
    for(i=2;i<=num/2;i++){
        if(num%i==0){
         count++;
            break;
        }
    }
   if(count==0 && num!= 1)
        printf("%d is a prime number",num);
   else
      printf("%d is not a prime number",num);
   return 0;
}

Output:
Enter a number: 5
5 is a prime number

To Print Prime numbers from 1 to 100:

int main(){
    int num,i,count;
  
    for(num = 1;num<=100;num++){
         count = 0;

         for(i=2;i<=num/2;i++){
             if(num%i==0){
                 count++;
                 break;
             }
        }
        
         if(count==0 && num!= 1)
             printf("%d ",num);
    }
  
   return 0;
}

Output:
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97

Write a C program whether the given number is Perfect number or not.

Definition of Perfect number: A positive integer n is called a perfect number if it is equal to the sum of all of its positive divisors, excluding n itself.


For example, 6 is perfect integer number, because 1, 2 and 3 are its proper positive divisors and 1+2+3=6.

The next perfect number is 28 because 1+2+4+7+14=28.
The next perfect number is 496 because
1+2+4+8+16+31+62+124+248=496.
/*program to check whether a number is perfect or not*/

#include<stdio.h>
#include<conio.h>
int main()
{
        int i,n,num,sum=0;
        printf("Enter a number : ");
        scanf("%d",&num);
        n=num;
        for(i=1; i<n; i++)
        {
               if(num%i==0)
                       sum=sum+i;
        }
        if(num==sum)
              printf("Given number is Perfect Number ");
        else
              printf("Given number is Not Perfect Number ");
    getch();
return 0;
}

Output:-
Enter a number : 7543
Given number is Not Perfect Number

Enter a number : 8128
Given number is Perfect Number

Write a C program to add, subtract, multiply and divide two numbers using functions

int add (int x, int y)
{
    int z;
    z = x + y;
    return (z);
}
int sub(int x, int y)
{
    int z;
    z = x - y;
    return (z);
}
int mul(int x, int y)
{
    int z;
    z = x * y;
    return (z);
}
int div(int x, int y)
{
    int z;
    z = x / y;
    return (z);
}
main ()
{
    int i,j,k,l,m,n;
    i = 10;
    j = 20;
    k = add(i, j); 
    l=sub(i,j);
    m=mul(i,j);
    n=div(i,j);
    printf("\n Sum %d",k);
    printf("\n Subtraction %d",l);
    printf("\n Multiplication %d",m);
    printf("\n divide %d",n);
}

Write a C program for matrix addition

Rule: Addition of two matrices is only possible if both matrices are of same size.

int main()
{
  int a[3][3],b[3][3],c[3][3],i,j;
  printf("Enter the First matrix->");
  for(i=0;i<3;i++)
      for(j=0;j<3;j++)
           scanf("%d",&a[i][j]);
  printf("\nEnter the Second matrix->");
  for(i=0;i<3;i++)
      for(j=0;j<3;j++)
           scanf("%d",&b[i][j]);
  printf("\nThe First matrix is\n");
  for(i=0;i<3;i++){
      printf("\n");
      for(j=0;j<3;j++)
           printf("%d\t",a[i][j]);
  }
  printf("\nThe Second matrix is\n");
  for(i=0;i<3;i++){
      printf("\n");
      for(j=0;j<3;j++)
      printf("%d\t",b[i][j]);
   }
   for(i=0;i<3;i++)
       for(j=0;j<3;j++)
            c[i][j]=a[i][j]+b[i][j];
   printf("\nThe Addition of two matrix is\n");
   for(i=0;i<3;i++){
       printf("\n");
       for(j=0;j<3;j++)
            printf("%d\t",c[i][j]);
   }
   return 0;
}

Write a C program for matrix subtraction

Rule: Subtraction of two matrices is only possible if both matrices are of same size. Suppose two matrices A and B is of same size m X n Subtraction of two matrices is defined as (A - B)ij = Aij - Bij Where 1 ≤ i ≤ m and 1 ≤ j ≤ n

int main(){
  int a[3][3],b[3][3],c[3][3],i,j;
  printf("Enter the First matrix->");
  for(i=0;i<3;i++)
      for(j=0;j<3;j++)
           scanf("%d",&a[i][j]);
  printf("\nEnter the Second matrix->");
  for(i=0;i<3;i++)
      for(j=0;j<3;j++)
           scanf("%d",&b[i][j]);
  printf("\nThe First matrix is\n");
  for(i=0;i<3;i++){
      printf("\n");
      for(j=0;j<3;j++)
           printf("%d\t",a[i][j]);
  }
  printf("\nThe Second matrix is\n");
  for(i=0;i<3;i++){
      printf("\n");
      for(j=0;j<3;j++)
      printf("%d\t",b[i][j]);
   }
   for(i=0;i<3;i++)
       for(j=0;j<3;j++)
            c[i][j]=a[i][j]-b[i][j];
   printf("\nThe Subtraction of two matrix is\n");
   for(i=0;i<3;i++){
       printf("\n");
       for(j=0;j<3;j++)
            printf("%d\t",c[i][j]);
   }
   return 0;
}

Write a C program to transpose the given matrix

Transpose: Transpose of a Matrix means changing Rows into Columns and vice-versa.

void main()
{
     int A[2][3] , B[3][2];
     int i, j;               /* 'i' used for rows and 'j' used for columns */
     clrscr();
     printf(" Enter the elements of A\n");
     for(i=0 ; i<2 ; i++)
     {
        for(j=0 ; j<3 ; j++)
        {
          scanf("%d" , &A[i][j] );
        }
     }
     printf(" Matrix is\n");
     for(i=0 ; i<2 ; i++)
     {
        for(j=0 ; j<3 ; j++)
        {
              printf("%d\t",A[i][j] );        /* '\t' used for Tab */ 
        }                                                          
        printf("\n");           /* '\n' used for next line character */
     }
     for(i=0 ; i<3 ; i++)
     {
         for(j=0 ; j<2 ; j++)
         {
              B[i][j] = A[j][i];
         }
     }
     printf(" After Transpose\n");
     for(i=0 ; i<3 ; i++)
     {
         for(j=0 ; j<2 ; j++)
         {
              printf("%d\t" , B[i][j] );                            
         }                                                           
         printf("\n");                                      
     }
     getch();
} 

Write a C program to find string palindrome without using String functions

int main()
{
   char text[100];
   int begin, middle, end, length = 0;
 
   gets(text);
 
   while ( text[length] != '\0' )
      length++;
 
   end = length - 1;
   middle = length/2;
 
   for( begin = 0 ; begin < middle ; begin++ )
   {
      if ( text[begin] != text[end] )
      {
         printf("Not a palindrome.\n");
         break;
      }
      end--;
   }
   if( begin == middle )
      printf("Palindrome.\n");
 
   return 0;
}

Write a C program for demonstrating Tower of Hanoi using Recursion

#include
#include
#include
void hanoi(int x, char from, char to, char aux)
{
    if(x==1)
    printf("Move Disk From %c to %c\n",from,to);
    else
    {
        hanoi(x-1,from,aux,to);
        printf("Move Disk From %c to %c\n",from,to);
        hanoi(x-1,aux,to,from);
    }
}

void main( )
{
    int disk;
    int moves;
    clrscr();
    printf("Enter the number of disks you want to play with:");
    scanf("%d",&disk);
    moves=pow(2,disk)-1;
    printf("\nThe No of moves required is=%d \n",moves);
    hanoi(disk,'A','C','B');
    getch( );
}


Output:
Enter the number of disks you want to play with: 3

The No of moves required is=7
Move Disk from A to C
Move Disk from A to B
Move Disk from C to B
Move Disk from A to C
Move Disk from B to A
Move Disk from B to C
Move Disk from A to C