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6 files changed, 220 insertions, 0 deletions

diff --git a/9p23.cpp b/9p23.cpp
new file mode 100644
index 0000000..432e77f
--- /dev/null
+++ b/9p23.cpp
@@ -0,0 +1,32 @@
+#include <iostream>
+#include <vector>
+
+/*
+ *
+ * 9.23
+ *
+ *
+ */
+
+int main () {
+
+	std::vector<int> c = {1};
+	if (c.size() == 1) {
+		// val and val2 are copies of the value of the first element in c
+		auto val = *c.begin(), val2 = c.front();
+		// val3 and val4 are copies of the of the last element in c
+		auto last = c.end();
+		auto val3 = *(--last); // can’t decrement forward_list iterators
+		auto val4 = c.back(); // not supported by forward_list
+
+		std::cout << val << "\n"
+				  << val2 << "\n"
+				  << val3 << "\n"
+				  << val4 << "\n";
+		if(val || val2 || val3 || val4) {}
+
+	}
+
+	
+	return 0;
+}
diff --git a/9p24.cpp b/9p24.cpp
new file mode 100644
index 0000000..23b0e0e
--- /dev/null
+++ b/9p24.cpp
@@ -0,0 +1,18 @@
+#include <iostream>
+#include <vector>
+
+/*
+ *
+ * 9.24
+ *
+ *
+ */
+
+int main () {
+
+	std::vector<int> a;
+	std::cout << a.at(0) << std::endl; //Exception
+	std::cout << a.front() << std::endl; // Segfault
+	std::cout << a.back() << std::endl; // Segfault
+	return 0;
+}
diff --git a/9p25.cpp b/9p25.cpp
new file mode 100644
index 0000000..0a14d6c
--- /dev/null
+++ b/9p25.cpp
@@ -0,0 +1,31 @@
+#include <iostream>
+#include <vector>
+
+/*
+ *
+ * 9.25
+ *
+ *
+ */
+
+int main () {
+
+	std::vector<int> slist;
+	auto elem1 = slist.begin();
+	auto elem2 = slist.end();
+	auto elem1end = slist.end();
+	auto elem2end = slist.end();
+	// All iterators above are the same
+	// And no, nothing happens.
+	if(elem1 == elem2) {
+		std::cout << "elem1 == elem2" << std::endl;
+		elem1 = slist.erase(elem1, elem2);
+	}
+
+	if(elem1end == elem2end) {
+		std::cout << "elem1end == elem2end" << std::endl;
+		elem1end = slist.erase(elem1end, elem2end);
+	}
+	
+	return 0;
+}
diff --git a/9p26.cpp b/9p26.cpp
new file mode 100644
index 0000000..2bef2ef
--- /dev/null
+++ b/9p26.cpp
@@ -0,0 +1,50 @@
+#include <iostream>
+#include <vector>
+#include <list>
+
+/*
+ *
+ * 9.26
+ *
+ *
+ */
+
+int main () {
+
+	int ia[] = { 0, 1, 1, 2, 3, 5, 8, 13, 21, 55, 89 };
+	std::list<int> li;
+	std::vector<int> vi;
+	for(decltype(std::size(ia)) i = 0 ; i != std::size(ia) ; ++i) {
+		li.push_back(ia[i]);
+		vi.push_back(ia[i]);
+	}
+
+	auto beg = li.begin();
+	for( ; beg != li.cend() ; ) {
+		if(*beg % 2 == 1) {
+			beg = li.erase(beg);
+		} else {
+			++beg;
+		}
+	}
+
+	auto begv = vi.begin();
+	for( ; begv != vi.cend() ; ) {
+		if(*begv % 2 == 1) {
+			++begv;
+		} else {
+			begv = vi.erase(begv);
+		}
+	}
+	
+	for(auto &a : li) {
+		std::cout << a << "\n";
+	}
+
+	std::cout << std::endl;
+	for(auto &a : vi) {
+		std::cout << a << "\n";
+	}
+
+	return 0;
+}
diff --git a/9p27.cpp b/9p27.cpp
new file mode 100644
index 0000000..07913f8
--- /dev/null
+++ b/9p27.cpp
@@ -0,0 +1,36 @@
+#include <iostream>
+#include <forward_list>
+
+/*
+ *
+ * 9.27
+ *
+ *
+ */
+
+int main () {
+
+	std::forward_list<int> flst = {0,1,2,3,4,5,6,7,8,9};
+	for(auto &a : flst) {
+		std::cout << a << "\n";
+	}
+	
+	auto bbeg = flst.before_begin();
+	auto beg = flst.begin();
+	auto end = flst.cend();
+	while(beg != end) {
+		if(*beg % 2 == 1) {
+			beg = flst.erase_after(bbeg);
+		} else {
+			bbeg = beg;
+			++beg;
+		}
+	}
+
+	std::cout << std::endl;
+	for(auto &a : flst) {
+		std::cout << a << "\n";
+	}
+	
+	return 0;
+}
diff --git a/9p28.cpp b/9p28.cpp
new file mode 100644
index 0000000..3098381
--- /dev/null
+++ b/9p28.cpp
@@ -0,0 +1,53 @@
+#include <iostream>
+#include <forward_list>
+
+/*
+ *
+ * 9.28
+ *
+ *
+ */
+
+std::forward_list<std::string> &ch9e28(std::forward_list<std::string> &fl, std::string findme, std::string s) {
+
+	bool success = false;
+	auto beg = fl.begin();
+	auto end = fl.cend();
+	while(beg != end) {
+		if(*beg == findme) {
+			beg = fl.insert_after(beg, s);
+			success = true;
+			break;
+		} else {
+			++beg;
+		}
+	}
+
+	if(success == false) {
+		auto sbeg = fl.begin();
+		auto sbbeg = fl.before_begin();
+		for(; sbeg != end ; ++sbeg, ++sbbeg) {
+			
+		}
+
+		fl.insert_after(sbbeg, s);
+		
+	}
+	
+	return fl;
+}
+
+int main () {
+
+	/*
+	  My solution felt a bit hacky but it works, whatever.
+	 */
+	std::forward_list<std::string> flm = {"HELLO", "AA", "YO", "HELL"};
+	std::string s = "HELLOafter";
+	ch9e28(flm, "HELLO", s);
+	for(auto &a : flm) {
+		std::cout << a << std::endl;
+	}
+	
+	return 0;
+}