Write a program in c plus plus to display the palindrome numbers between 10 and 1000?

Answer 1

#include<iostream>

unsigned int reverse(unsigned int num, unsigned int base=10)

{

unsigned int rev=0;

while( num )

{

rev*=base;

rev+=num%base;

num/=base;

}

return( rev );

}

int main()

{

std::cout<<"Palindromic numbers from 10 to 1000\n"<<std::endl;

for( unsigned int num=10; num<=1000; ++num)

if( num==reverse(num))

std::cout<<num<<std::endl;

}

Answer 2

It is impossible to print all palindromic numbers since numbers are infinite. You should either limit your range of numbers to the maximum number that can be stored in your variable. For example, a 32-bit unsigned int can handle integers in the range 0 to 4,294,967,295 while a 64-bit unsigned int can handle integers in the range 0 to 18,446,744,073,709,551,616. If you need to handle larger integers than this you'd be best advised to implement a user-defined class that can handle the range you desire.

To determine if an integer is palindromic, convert the number to a character array (a string) then set two pointers, one to the first character the other to the last character. While the first point is less than the last pointer and the values being pointed at are the same value, increment the first pointer and decrement the last pointer. If the values differ at any point, the number is not palindromic. When the pointers are equal or pass each other, the number is definitely palindromic.

For example:

bool is_palindrome(std::string num)

{

size_t first = 0;

size_t last = num.size()-1;

while( first<last )

{

if (num[first]!=num[last])

return false; ++first;--last;

}

return true;

}

Answer 3

This can be accomplished by the use of nested loops. The outer loop is used to iterate from 1 to 10000 while the inner loop is used to determine the palindrome numbers.

Here is the code snippet:

int i=1, temp, n=10000, rev;

while( i<=n){

temp = i;

rev = 0;

while( temp != 0){

rev = rev*10 + temp%10;

temp /= 10;

}

if( rev == i)

printf("%d\n", i);//printing the palindromic numbers

i++;

}