more

3 files changed, 72 insertions, 0 deletions

diff --git a/4p31.cpp b/4p31.cpp
new file mode 100644
index 0000000..07bc64f
--- /dev/null
+++ b/4p31.cpp
@@ -0,0 +1,26 @@
+#include <iostream>
+#include <vector>
+
+/*
+ *
+ * 4.31
+ *
+ * There is no difference, because what is returned is discarded.
+ * ++ix and --cnt is technically better because we return nothing
+ * but there isnt a difference because both programs do the same thing.
+ */
+
+int main () {
+	
+	std::vector<int> ivec(10);
+	std::vector<int>::size_type cnt = ivec.size();
+	for(std::vector<int>::size_type ix = 0 ; ix != ivec.size() ; ix++, cnt--) {
+		ivec[ix] = cnt;
+	}
+
+	for(auto a : ivec) {
+		std::cout << a << std::endl;
+	}
+	
+	return 0;
+}
diff --git a/4p32.cpp b/4p32.cpp
new file mode 100644
index 0000000..346b82e
--- /dev/null
+++ b/4p32.cpp
@@ -0,0 +1,23 @@
+#include <iostream>
+
+/*
+ *
+ * 4.32
+ *
+ * We have a pointer thats basically like a begin() iterator
+ * We have ix that starts at 0
+ * We keep looping as long as ix is not equal to the size
+ * We keep looping as long as ptr does not point to one past the last element in ia
+ * This ensures that we can safely do stuff to the array inside the loop
+ */
+
+int main () {
+
+	constexpr int size = 5;
+	int ia[size] = {1,2,3,4,5};
+	for (int *ptr = ia, ix = 0 ; ix != size && ptr != ia+size ; ++ix, ++ptr){
+		/* . . . */
+	}
+
+	return 0;
+}
diff --git a/4p33.cpp b/4p33.cpp
new file mode 100644
index 0000000..fa4f199
--- /dev/null
+++ b/4p33.cpp
@@ -0,0 +1,23 @@
+#include <iostream>
+
+/*
+ *
+ * 4.33
+ *
+ *
+ */
+
+int main () {
+
+	bool someValue = true;
+	int res;
+	int x = 1;
+	int y = 1;
+	// (sameValue ? (++x, ++y) : --x), --y
+	res = someValue ? ++x, ++y : --x, --y;
+	std::cout << res << " res"<< std::endl;
+	std::cout << x << " x" << std::endl;
+	std::cout << y << " y" << std::endl;
+	
+	return 0;
+}