3 files changed, 31 insertions, 6 deletions
diff --git a/6p18.cpp b/6p18.cpp
index 58d5fbf..1d0bc41 100644
--- a/6p18.cpp
+++ b/6p18.cpp
@@ -1,12 +1,14 @@
-#include <iostream>
 
 /*
  *
- * Description
+ * 6.18
  *
  *
  */
 
 int main () {
+	
+	// bool compare(matrix &rm1, matrix &rm2);
+	// std::vector<int>::iterator change_val(int i, std::vector<int>::iterator iter);
 	return 0;
 }
diff --git a/6p19.cpp b/6p19.cpp
index 58d5fbf..af813f4 100644
--- a/6p19.cpp
+++ b/6p19.cpp
@@ -1,12 +1,30 @@
-#include <iostream>
 
 /*
  *
- * Description
+ * 6.19
  *
  *
  */
 
 int main () {
+
+	/*
+	double calc(double);
+	int count(const string &, char);
+	int sum(vector<int>::iterator, vector<int>::iterator, int);
+	vector<int> vec(10);
+
+	(a)
+	calc(23.4, 55.1); // illegal, only 1 argument
+	
+	(b)
+	count("abcda", ’a’); // legal
+
+	(c)
+	calc(66); // legal
+	
+	(d)
+	sum(vec.begin(), vec.end(), 3.8); // legal
+	*/
 	return 0;
 }
diff --git a/6p20.cpp b/6p20.cpp
index 58d5fbf..c2b0b0b 100644
--- a/6p20.cpp
+++ b/6p20.cpp
@@ -1,12 +1,17 @@
-#include <iostream>
 
 /*
  *
- * Description
+ * 6.20
  *
  *
  */
 
 int main () {
+
+	/*
+	  We should do it when we only need to read the data.
+	  There is no point accidentally writing to something we did not intend to write to.
+	  Because if we had used const we would not be allowed to.
+	 */
 	return 0;
 }