Question

How to find all 3 digits numbers that are palindrome in base 10 and base 2 with C

Answer 1

#include <stdio.h>
#include <string.h>
#include <stdbool.h>

void toBinary(unsigned int number, char binaryNumber[]) {
    int i = 0;

    while (number != 0) {
        binaryNumber[i] = (number % 2) + '0';
        i++;
        number /= 2;
    }

    _strrev(binaryNumber);
}

int isBinaryRepresentationOfNumberPalindrome(unsigned int number) {
    char binaryNumber[17] = "";

    toBinary(number, binaryNumber);

    char revBinaryNumber[17] = "";
    strcpy(revBinaryNumber, binaryNumber);
    _strrev(revBinaryNumber);

    return strcmp(binaryNumber, revBinaryNumber) == 0;
}

bool isPalindrome(int n) {
    int reverse = 0, temp = n;

    while (temp != 0) {
        int remainder = temp % 10;
        reverse = (reverse * 10) + remainder;
        temp = temp / 10;
    }

    return n == reverse;
}

int main(void) {

    for (int i = 100; i < 1000; i++) {
        if (isPalindrome(i) && isBinaryRepresentationOfNumberPalindrome(i)) {
            char binaryNumber[17] = "";
            toBinary(i, binaryNumber);

            printf("%d %s\n", i, binaryNumber);
        }
    }

    return 0;
}





/*
run:

313 100111001
585 1001001001
717 1011001101

*/

 

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