C

DeitelC/Chapter5/exercise5-42.c

@@ -0,0 +1,9 @@
+#include <stdio.h>
+
+int main(void) {
+	int c = '\0'; // variable to hold character input by user
+	if ((c = getchar()) != EOF) {
+		printf("%c", c);
+		main();
+	}
+}

DeitelC/Chapter5/exercise5-43.c

@@ -0,0 +1,23 @@
+#include <stdio.h>
+int mystery(int a, int b); // function prototype
+
+int main(void) {
+	printf("%s", "Enter two positive integers: ");
+	int x = 0; // first integer
+	int y = 0; // second integer
+	scanf("%d%d", &x, &y);
+	printf("The result is %d\n", mystery(x, y));
+}
+
+// Parameter b must be a positive integer
+// to prevent infinite recursion
+int mystery(int a, int b) {
+// base case
+	if (1 == b) {
+		return a;
+	} else if (b > 1) { // recursive step
+		return a + mystery(a, b - 1);
+	} else {
+		return -a + mystery(a, b + 1);
+	}
+}

DeitelC/Chapter5/greatestCommonDivisor.c

@@ -0,0 +1,19 @@
+#include <stdio.h>
+
+int gcd (int, int);
+
+int main (void) {
+	printf("%d\n", gcd(15, 20));
+	return 0;
+}
+
+
+
+
+int gcd (int x, int y) {
+	if(!y) {
+		return x;
+	} else {
+		return gcd(y, x % y);
+	}
+}

DeitelC/Chapter5/recursiveMain.c

@@ -0,0 +1,11 @@
+#include <stdio.h>
+
+int main (void) {
+	static int count = 1;
+
+	printf("%d\n", count++);
+	if (count <= 5) {
+		main();
+	}
+	return 0;
+}

DeitelC/Chapter5/recursivePrime.c

@@ -0,0 +1,28 @@
+#include <stdio.h>
+
+int isPrimeX (int, int);
+int isPrime (int);
+
+int main (void) {
+	printf("%d\n", isPrime(11));
+	return 0;
+}
+
+int isPrime (int x) {
+	return isPrimeX (x, 2);
+}
+
+
+int isPrimeX (int x, int i) {
+	if (x <= 2) {
+		return (x == 2) ? 1 : 0;
+	}
+	if (x % i == 0){
+		return 0;
+	}
+	if (i * i > x) {
+		return 1;
+	}
+
+	return isPrimeX (x, i + 1);
+}