I'm trying to create a piece of C++ code which will only allow a user to enter odd numbers.
If an even number is entered, the program must tell the user to enter only an odd number.

Im comfortable with the whole output bit in the 2nd line above, but i have no idea where to start with regards to analysing the number!

welcome aboard....please post what you've got so that w can guide you. Here is some pointers:
1. start with your headers, you'll need to figure out which ones you'll need:

#include<iostream>

2. You need:

using namespace std;
int main()

3. you need to declare some variables:

int num;

4. Ask the user to input a number:

cout << "Enter an integer: ";

5.Allow the user to input:

cin >> num;

6. For the actual calculation, we use the modulos (%) operator. From basic math/algebra, you ought to know theoretically, how to calculate even and odd numbers....do they have remainders....if they do...what's the remainder.
7.

if (expression)
statement1
else
statement2

The above test to see if the number is odd or not...if it is, do something...if it's not....do something.
8. Then you'll need output statements (answers to provide) to you professor:

cout << num << " is an odd number" << endl;

In the future....search the internet(GOOGLE)...or the frum to see if the problem has been covered already.
10. most importantly...to be successful in c++ you'll simply have to do the work....and practice...
Hope this helps...have a good day!

If a number is divisible by 2, it's even. If it's not divisible by 2, it's odd. You can find out if a number is divisible by 2 by finding the remainder of division by 2. C++ has a remainder operator, %. So it stands to reason that if you have a number x, you can say:

#include<stdio.h>
#include<conio.h>
#include<Windows.h>
#include <time.h>
#define A 3// name a constant
struct book
{
char name[20];
int ID_card;
int contact_number;
int dd;
int mm;
int yy;
long int booking_ID ; ...