Write a C program to determine the given integer is Perfect number or not.

Perfect number:- Sum of the factorials of a individual digit is known as Perfect number
Ex:- 145 = 1! + 4! + 5!
=> 145 = 1 + 24 + 120
==> 145 = 145

So '145' is a Perfect number.

#include(stdio.h) // place this '<' & '>' instead of '(' & ')' before stdio.h
#include(conio.h)
void main( )
{
int no, rem, sum=0, temp, fact;
clrscr( );
printf("Enter the required number:");
scanf("%d", &no);
temp=no;
while(no>0)
{
fact=1;
for( rem= no%10 ; rem>=1; rem--) { fact=fact*rem; }
sum = sum+ fact;
no = no/10;
}
if(temp == sum)
printf("\n%d is Perfect number", temp);
else
printf("\n%d is not a Perfect number", temp);
getch();
}

Output:-
Enter the required number: 145

145 is Perfect number.

Note:- If u have any doubt regarding this program or logic, please feel free to contact me.

Write a C program to check whether the given integer Prime number or not.

Method: 1

#include(stdio.h) // place this '<' & '>' instead of '(' & ')' before stdio.h
#include(conio.h)
int main( )
{
int no, flag=0, x=2;
clrscr( );
printf("Enter the required number to check:");
scanf("%d", &no);
while(x<=no/2) {
if(no%x==0)
{
flag=1;
break;
}
x++;
}
if(flag==0)
printf("\nPrime number.");
else
printf("\nNot a Prime number.");
getch( );
return o;
}

Output:-
Enter the required number: 23
Prime number.

Method: 2 // Prime number or not

#include(stdio.h) // place this '<' & '>' instead of '(' & ')' before stdio.h
#include(conio.h)
int main( )
{
int no, ct=0 , x=1;
clrscr( );
printf("Enter the required number to check:");
scanf("%d", &no);
while(x<=no)
{
if(no%x==0)
{ ct++; }
x++;
}
if(flag==0)
printf("\nPrime number.");
else
printf("\nNot a Prime number.");
getch( );
return o;
}

Output:-
Enter the required number: 21
Not a Prime number.

Note:- If u have any doubt regarding this program or logic, please feel free to contact me.

Write a C program to solve the Towers of Hanoi problem using Recursive function.

#include(stdio.h) // place this '<' & '>' instead of '(' & ')' before stdio.h
#include(conio.h)
#include(math.h)
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

Note:- If u have any doubt regarding this program or logic, please feel free to contact me.

Write a C program to find the GCD (greatest common divisor) of two given integers using Recursive function.

#include(stdio.h) // place this '<' & '>' instead of '(' & ')' before stdio.h
#include(conio.h)
int gcd (int, int); //func. declaration.
void main( )
{
int a, b, res;
clrscr( );
printf("Enter the two integer values:");
scanf("%d%d", &a, &b);
res= gcd(a, b); // calling function.
printf("\nGCD of %d and %d is: %d", a, b, res);
getch( );
}
int gcd( int x, int y) //called function.
{
int z;
z=x%y;
if(z==0)
return y;
gcd(y,z); //recursive function
}

Note:- If u have any doubt regarding this program or logic, please feel free to contact me.

Write a C program to find the GCD (greatest common divisor) of two given integers without using recusive function

(a). Without using Recursive function.

#include(stdio.h) // place this '<' & '>' instead of '(' & ')' before stdio.h
#include(conio.h)
void gcd (int, int); //func. declaration.
void main( )
{
int a, b;
clrscr( );
printf("Enter the two integer values:");
scanf("%d%d", &a, &b);
printf("\nGiven numbers are: %d and %d", a, b);
gcd(a, b); // calling function.
getch( );
}
void gcd( int x, int y) //called function.
{
int z;
for( ; ; ) //This is empty for loop.
{
z= x%y;
if( z==0) break;
x=y;
y=z;
}
printf("\nThe GCD is: %d", y);
}

Note:- Take the values as 23 and 3 , then GCd is 3.
This logic works, when a>b. (ie., 23>3 )
I'm not mentioned the logic when b>a. ( for that, we need if-else statement)

Explanation:-
Here i'm taking empty for loop becoz i dont have initial value , condition and increment or decrement.
This for loop will ends, when 'z' becomes zero. ie.,(z==0)

Write a C program to delete n Characters from a given position in a given string.

//without using functions.

#include(stdio.h) // place this '<' & '>' instead of '(' & ')' before stdio.h
#include(string.h)
void main()
{
char st[20],temp[20];
int pos,i,j,ct=0,n;
clrscr();
printf("Enter the string:");
gets(st);
printf("\nEntre the index position:");
scanf("%d",&pos);
printf("\nEnter the no.of characters:");
scanf("%d",&n);
if(pos<=strlen(st)) {
for(i=0;i<=strlen(st);i++) {
if(i==pos)
{
for(j=0;st[i]!='\0';j++) // to store the 'st' in 'temp' from a giv pos
{
temp[j]=st[i];
i++;
}
temp[j]='\0';
i=pos;
//to delete the 'n' char and after restore the temp in st.
for(j=0;temp[j]!='\0';j++)
{
ct++;
if(ct>n)
{
st[i]=temp[j];
i++;
}
}
st[i]='\0';
}
}
printf("\n\nAfter deletion the string: %s",st);
}
else
printf("\nSorry, we cannot delete from that position.");
getch();
}

Note:- If u have any doubt regarding this program or logic, please feel free to contact me.

Write a C program to insert a sub-string in to given main string from a given position.

//Without using Functions.

#include(stdio.h) // place this '<' & '>' instead of '(' & ')' before stdio.h
#include(string.h)
void main( )
{
char st[20],sub[10],temp[10];
int pos, i, j;
clrscr( );
printf("Enter the main string:");
gets(st);
printf("\nEnter the substring to insert:");
gets(sub);
printf("Enter the index position:");
scanf("%d",&pos);
if(pos<=strlen(st)) {
for(i=0;i<=strlen(st);i++) {
if(i==pos)
{
for(j=0;st[i]!='\0';j++) // to store the 'st' to 'temp' from given position.
{
temp[j]=st[i];
i++;
}
temp[j]='\0';
i=pos;
for(j=0;sub[j]!='\0';j++) // to insert a sub-str to main string.
{
st[i]=sub[j];
i++;
}
for(j=0;temp[j]!='\0';j++) // Lastly to insert the 'temp' to 'st' after sub-str.
{
st[i]=temp[j];
i++;
}
st[i]='\0';
}}
printf("\nAfter adding the sub-string: %s",st);
}
else
printf("\nSorry, it is not possible to insert a substring in that position.");
getch();
}

Note:- If u have any doubt regarding this program or logic, please feel free to contact me.

Write a C program to read in two numbers, x and n, and then compute the sum of this geometric progression: 1+x+x2+x3+………….+xn

#include(stdio.h) // place this '<' & '>' instead of '(' & ')' before stdio.h
#include(conio.h)
#include(math.h)
int main( )
{
int x, n, sum,power;
clrscr( );
printf("Enter the values of x and n:");
scanf("%d%d", &x, &n);
if(n<0 style="font-weight: bold; color: rgb(255, 0, 0);">
{
printf("\nSorry, the formula does not make sense for negative exponents & values");
printf("Enter the values of x and n:");
scanf("%d%d", &x, &n);
sum=1;
for(power=1; power <=n; power++) {
sum=sum+ pow(x,power); }
printf("X value is: %d \nN value is: %d", x, n);
printf("\nSum of the given geometric progression: %d", sum);
}
else
{
sum=1;
for(power=1; power <=n; power++) {
sum=sum+ pow(x,power); }
printf("X value is: %d \nN value is: %d", x, n);
printf("\nSum of the given geometric progression: %d", sum);
}
getch( );
return 0;
}

Output:-
case 1: Suppose x=5, n=3
X value is: 5
N value is: 3
Sum of the given geometric progression: 156
ie., 1+ 5 + 25 + 125 = 156

case 2: Suppose n=-2 or x=-5 then the following message will be displays and it ask for another new values,

Sorry, the formula does not make sense for negative exponents & values.
Enter the values of x and n:5
3
X value is: 5
N value is: 3
Sum of the given geometric progression: 156

Write C programs that use both recursive and non-recursive functions to find the factorial of a given integer.

(i). to find the factorial of a given integer
(a).without using recursive function.

#include(stdio.h) // place this '<' & '>' instead of '(' & ')' before stdio.h
#include(conio.h)
int fact( int); // function declaration
int main( )
{
int no,result;
clrscr( );
printf("Enter the required number:");
scanf("%d", &no);
result = fact( no);
printf("\n %d Factorial is : %d", no, result);
getch( );
return 0;
}
int fact(int n)
{
int ft,
for( ft=1; n>=1; n--)
ft=ft*n;
return ft;
}

Output:- 4 Factorial is : 24

(a).using recursive function.

#include(stdio.h) // place this '<' & '>' instead of '(' & ')' before stdio.h
#include(conio.h)
int fact( int); // function declaration
int main( )
{
int no,result;
clrscr( );
printf("Enter the required number:");
scanf("%d", &no);
result = fact( no);
printf("\n %d Factorial is : %d", no, result);
getch( );
return 0;
}
int fact(int n)
{
int ft,
if( n==1)
return 1;
else
ft= n*fact (n-1);
return ft;
}

Output:- 4 Factorial is : 24

Write a C program to construct a pyramid of numbers.

/*
1
2 3
4 5 6
7 8 9 10
11 12 13 14 15
*/

#include(stdio.h) // place this '<' & '>' instead of '(' & ')' before stdio.h
#include(conio.h)
int main( )
{
int r, c, num=1 ,len;
clrscr( );
printf("Enter the required no. of rows:");
scanf("%d", &len);
for( r=1; r< =len; r++ ) {
printf("\n");
for(c=1 ; c<=r; c++) {
printf("%2d", num);
num++; }
}
getch( );
return 0;
}
Explanation:-
Here 'r' indicates row,
'c' indicates column and 'len' indicates length of the pyramid.
And lastly 'num=1' for generating pyramid of numbers.
This 'c<=r' is required becoz when row is incremented, column value is also incremented.
Note:- If U have any doubts regarding this program, contact with me through my email-id.