added programs

programs/p310/main.c

@@ -0,0 +1,69 @@
+#include <stdio.h>
+
+#define NON_EQUAL 0
+#define ONE_EQUAL 1
+#define ALL_EQUAL 2
+
+#ifndef USE_ALT
+
+int main(void) {
+    int a, b, c;
+
+    printf("Int A: ");
+    scanf("%d", &a);
+    printf("Int B: ");
+    scanf("%d", &b);
+    printf("Int C: ");
+    scanf("%d", &c);
+
+    if (a == b && a == c) {
+        printf("All three values are equal.\n");
+    } else if (a != b && a == c) {
+        printf("Two values are equal.\n");
+    } else if (a != c && a == b) {
+        printf("Two values are equal.\n");
+    } else if (b == c) {
+        printf("Two values are equal.\n");
+    } else {
+        printf("All three values are different.\n");
+    }
+
+    return 0;
+}
+
+#endif // !(defined(USE_ALT))
+
+#ifdef USE_ALT
+
+// alternetive answer
+int main(void) {
+    int flag = 0; // remember, boolean in C is just integer
+
+    int a, b, c;
+
+    printf("Int A: ");
+    scanf("%d", &a);
+    printf("Int B: ");
+    scanf("%d", &b);
+    printf("Int C: ");
+    scanf("%d", &c);
+
+    flag += a == b;
+    flag += a == c;
+
+    if (flag != ALL_EQUAL) {
+        flag += b == c;
+    }
+
+    if (flag == NON_EQUAL) {
+        printf("All three values are different.\n");
+    } else if (flag == ONE_EQUAL) {
+        printf("Two values are equal.\n");
+    } else {
+        printf("All three values are equal.\n");
+    }
+
+    return 0;
+}
+
+#endif // defined(USE_ALT)