Check if a number is prime.

misc/Prime.c

@@ -0,0 +1,25 @@
+#include <stdio.h>
+
+int isPrime(int x) {
+    if (x == 1)
+        return 0;
+    if (x % 2 == 0)
+        return 0;
+    for (int i = 3; i < x; i++) { // May replace x with sqrt(x)
+        if (x%i == 0)
+            return 0;
+    }
+    return 1;
+    
+}
+
+int main() {
+    int a;
+    printf("Input a number to see if it is a prime number:\n");
+    scanf("%d", &a);
+    if (isPrime(a))
+        printf("%d is a prime number.\n", a);
+    else
+        printf("%d is not a prime number.\n", a);
+    return 0;
+}