Palindromic primes: Difference between revisions

Content deleted Content added

Inline

@@ Line 160: / Line 160: @@
 3 5 7 11 101 131 151 181 191 313 353 373 383 727 757 787 797 919 929
 Palindromic primes 1-999: 20
+</pre>
+=={{header|C}}==
+<syntaxhighlight lang="C">
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#include <stdbool.h>
+bool ispalindromic(int n) {
+    int i, j;
+	char s[20];
+	itoa(n, s, 10);
+	i = 0;
+	j = strlen(s) - 1;
+	while (i < j) {
+		if (s[i] != s[j]) return false;
+		i++;
+		j--;
+	}
+	return true;
+}
+bool isprime(int n) {
+	int i, lim, count;
+	if (n < 2) return false;
+	if (n % 2 == 0) return (n == 2);
+	lim = (int) floor(sqrt((float) n));
+	for (i = 3; i <= lim; i += 2) {
+		if (n % i == 0) return false;
+	}
+	return true;
+}
+int main(void) {
+	int i, count;
+	count = 0;
+	for (i = 2; i <= 1000; i++) {
+		if (isprime(i) && ispalindromic(i)) {
+			printf("%d ", i);
+			count++;
+		}
+	}
+	printf("\nFound %d palindromic primes\n", count);
+	return EXIT_SUCCESS;
+}
+</syntaxhighlight>
+{{out}}
+<pre>
+3 5 7 11 101 131 151 181 191 313 353 373 383 727 757 787 797 919 929
+Found 20 palindromic primes
 </pre>