# C Exercises: Find all prime palindromes in the range of two given numbers x and y

## C Basic Declarations and Expressions: Exercise-90 with Solution

Write a C program to find all prime palindromes in the range of two given numbers x and y (5 <= x<y<= 1000,000,000).

A number is called a prime palindrome if the number is both a prime number and a palindrome.

**Sample Solution:**

**C Code:**

```
#include<stdio.h>
// Function to compute a palindrome number from a given number
int compute(int n){
if(n == 9) // Special case for n = 9
return 11; // Return 11
int res = 0, tmp, base = 1;
// Loop to reverse the digits of n
for(tmp = n / 10; tmp> 0; tmp = tmp / 10){
res = res * 10 + tmp % 10; // Build the reversed number
base *= 10;
}
return n * base + res; // Combine the original and reversed numbers
}
// Function to check if a number is prime and print it if it is
int prime(int n){
int i;
int flag;
// Loop to check for factors of n
for(i = 2; i * i<= n; i++){
flag = 0;
if(n % i == 0){
flag = 1; // Set flag to indicate non-prime
break;
}
}
if(flag == 0){ // If flag remains 0, n is a prime number
printf("%d\n", n); // Print the prime number
}
}
int main(){
int x, y, temp = 0;
printf("Input two numbers (separated by a space):\n");
scanf("%d %d", &x, &y);
printf("List of prime palindromes:\n");
// Loop to generate and check palindrome numbers
for(; temp <= y; x++){
temp = compute(x);
prime(temp);
}
return 0; // Indicate successful execution of the program
}
```

Sample Output:

Input two numbers (separated by a space): List of prime palindromes: 0 1

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