Program to find any number inside another number in C.

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/*Program to find given numbers presence in another number in C

or 

Program to find any number inside another number in C.
 */

#include<stdio.h>
#include<conio.h>

void main()
{
int num,num1,nf,rem,newnum,len,i,c;
clrscr();

len=0;
newnum=0;
c=0; //Counter Variable

printf("\n\tNumber Finder");
printf("\n-------------------------");
printf("\nEnter a number:");
scanf("%d",&num);

/*Single Digit number */
printf("\nEnter number to find:");
scanf("%d",&nf);


num1=num; //to save actual number


/*Number Reverse */
while(num1>=1)
{
rem=num1%10;
num1=num1/10;
newnum=newnum*10+rem; 
len++;
}


for(i=1;i<=len;i++)
{
rem=newnum%10;
newnum=newnum/10;

if(rem==nf)
{
printf("\nNumber %d is present in %d at position %d.",nf,num,i);
}
else
{
c++; //Counter Variable
}
}


if(c==len)  //Checking for absence 
{
printf("\nNumber Not Found!!!");
}

getch();

}

Program to find input number is prime or not with special case in C.

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/*Program to find input number is prime or not*/

#include<stdio.h>
#include<conio.h>
void main()
{
int num,i,c;
c=0; //counter
clrscr();

printf("\nEnter any number:");
scanf("%d",&num);

clrscr();  //for clear screen

printf("\n-------------------------------");
printf("\nNumber entered is: %d",num);
printf("\n-------------------------------");


if(num==0)
{
printf("\nZero entered!!"); //Zero case
}
else
{
/*Prime finder */
for(i=2;i<=(num/2);i++)
{ /*start from 2 because every number is divisible by 1 */
/* i<=(num/2) because any number can be completely divisible by only half or less than itself.*/
if(num%i==0)
{
c=1;
}
}

/*Prime checker */
if(c==0)
{
printf("\n%d is prime",num);
}
else{
printf("\n%d is not a prime",num);
}

}

printf("\n------------------------------");

getch();
}

Program to find input number is prime or not using for loop in C.

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/*Program to find input number is prime or not*/

#include<stdio.h>
#include<conio.h>
void main()
{
int num,i,c;
c=0; //counter
clrscr();

printf("\nEnter any number:");
scanf("%d",&num);

clrscr();  //for clear screen

printf("\n-------------------------------");
printf("\nNumber entered is: %d",num);
printf("\n-------------------------------");


/*Prime finder */
for(i=2;i<num;i++)
{ /*start from 2 because every number is divisible by 1 */
if(num%i==0)
{
c=1;
}
}

/*Prime checker */
if(c==0)
{
printf("\n%d is prime",num);
}
else{
printf("\n%d is not a prime",num);
}

printf("\n------------------------------");

getch();
}

Program to find input number is prime or not using while loop in C.

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/*Program to find input number is prime or not*/

#include<stdio.h>
#include<conio.h>
void main()
{
int num,i,c;
c=0; //counter
clrscr();

printf("\nEnter any number:");
scanf("%d",&num);

clrscr();  //for clear screen

printf("\n-------------------------------");
printf("\nNumber entered is: %d",num);
printf("\n-------------------------------");

i=2;
/*start from 2 because every number is divisible by 1 */

/*Prime finder */
while(i<num)
{
if(num%i==0)
{
c=1;
}
i++;
}

/*Prime checker */
if(c==0)
{
printf("\n%d is prime",num);
}
else{
printf("\n%d is not a prime",num);
}

printf("\n------------------------------");

getch();
}