diff --git a/array2.cpp b/array2.cpp
new file mode 100644
index 0000000..218787a
--- /dev/null
+++ b/array2.cpp
@@ -0,0 +1,22 @@
+#include <iostream>
+using namespace std;
+
+void printArray(int arr[], int size){
+  for(int i=0; i < size; i++){
+    cout << arr[i] << endl;
+  } 
+}
+
+int main(){
+  //set aside memory for 20 integers
+  int myArray[20];
+  for(int i = 0; i < 20; i++){
+    myArray[i] = i*i; // myArray_i = i^2
+  }
+  
+  //for(int i = 0; i < 20; i++){
+  //  cout << myArray[i] << endl;
+  //}
+  printArray(myArray,20);
+  return 0;
+}
\ No newline at end of file
diff --git a/array3.cpp b/array3.cpp
new file mode 100644
index 0000000..bbbb8bc
--- /dev/null
+++ b/array3.cpp
@@ -0,0 +1,43 @@
+#include <iostream>
+using namespace std;
+
+void printRow(string name, string species, int age){
+  cout << "Pet: " << name << " is a " << species << " and is " << age << " year(s) old" << endl;
+}
+
+int main(){
+  const int arraySize = 5;
+  string petName[arraySize];
+  string petSpecies[arraySize];
+  int petAge[arraySize];
+  // populate arrays
+  for(int i=0; i < arraySize; i++){
+    cout << "Pet name: ";
+    cin >> petName[i];
+    cout << "Pet species: ";
+    cin >> petSpecies[i];
+    cout << "Pet age: ";
+    cin >> petAge[i];
+  }
+
+  // modify this program to:
+  // ask for a pet species
+  // and a maximum age
+  // and print only entries that match that
+  // hint: put an if-statement in the for loop below
+  int maxAge = 0;
+  string species;
+
+  cout << "Max age: ";
+  cin >> maxAge;
+  cout << "Species: ";
+  cin >> species;
+  //print arrays:
+  for(int i=0; i < arraySize; i++){
+    if(petAge[i] <= maxAge && petSpecies[i] == species){
+      printRow(petName[i],petSpecies[i],petAge[i]);
+    }
+  }
+  
+  return 0;
+}
\ No newline at end of file
diff --git a/find1.cpp b/find1.cpp
new file mode 100644
index 0000000..6b2d967
--- /dev/null
+++ b/find1.cpp
@@ -0,0 +1,16 @@
+#include <iostream>
+#include <string>
+using namespace std;
+
+int main(){
+  string str1 = "My head is full of rocks, rocks I say!";
+  string str2 = "paper";
+
+  cout << int(str1.find(str2)) << endl;
+
+  // let's check what happens at runtime if I access
+  // outside the length of a string
+
+  cout << str2.length() << endl;
+  return 0;
+}
\ No newline at end of file
diff --git a/fun2.cpp b/fun2.cpp
new file mode 100644
index 0000000..f8b52b2
--- /dev/null
+++ b/fun2.cpp
@@ -0,0 +1,15 @@
+#include <iostream>
+using namespace std;
+
+int sillyFun(int num){
+  num = num + 1;
+  return num;
+}
+// ourNumber = sillyFun(ourNumber) "equivalent" to pass-by-reference??
+
+int main(){
+  int ourNumber = 10;
+  cout << "sillyFun returns: " << sillyFun(ourNumber) 
+    << endl;
+  cout << "ourNumber is: " << ourNumber << endl;
+}
\ No newline at end of file
diff --git a/prototype1.cpp b/prototype1.cpp
new file mode 100644
index 0000000..33256c1
--- /dev/null
+++ b/prototype1.cpp
@@ -0,0 +1,16 @@
+#include <iostream>
+using namespace std;
+
+int adder(int num1, int num2);
+int rec(int num);
+
+int main(){
+
+  adder(1,2);
+  return 0;
+}
+
+int adder(int num1, int num2){
+  cout << "Look I'm adding" << endl;
+  return num1 + num2;
+}
diff --git a/sarcasmCase.cpp b/sarcasmCase.cpp
new file mode 100644
index 0000000..d9a8ae1
--- /dev/null
+++ b/sarcasmCase.cpp
@@ -0,0 +1,24 @@
+#include <iostream>
+#include <cctype>
+#include <cstdlib>
+using namespace std;
+
+string sarcasmCase(string s){
+  for(int i =0; i < s.length(); i++){
+    if(rand() % 2 == 0){
+      s[i] = toupper(s[i]);
+    }
+    else{
+      s[i] = tolower(s[i]);
+    }
+  }
+  return s;
+}
+
+int main(){
+  srand(time(0));
+
+  string str = "you can't do that!";
+
+  cout << sarcasmCase(str) << endl;
+}
\ No newline at end of file
diff --git a/substring.cpp b/substring.cpp
new file mode 100644
index 0000000..6d44a0e
--- /dev/null
+++ b/substring.cpp
@@ -0,0 +1,18 @@
+#include <iostream>
+#include <string>
+using namespace std;
+
+int main(){
+  string str1 = "My head is full of rocks, rocks I say!";
+  string str2 = "rock";
+
+  int pos = str1.find(str2);
+  cout << str1.substr(pos,str2.length()) << endl;
+  cout << str1.substr(pos,str2.length()+1) << endl;
+  cout << (str1.substr(pos,0) == "") << endl;
+
+  cout << str1.substr(pos,string::npos) << endl;
+  cout << int(string::npos) << endl;
+  
+  return 0;
+}
\ No newline at end of file
diff --git a/switch1.cpp b/switch1.cpp
new file mode 100644
index 0000000..c98880c
--- /dev/null
+++ b/switch1.cpp
@@ -0,0 +1,40 @@
+#include <iostream>
+using namespace std;
+
+int main(){
+  int option = 0;
+  cout << "Enter a number between 1 and 5" << endl;
+
+  cin >> option;
+/*
+  if(option == 1){
+    //...
+  }
+  else if(option == 2){
+    //...
+  } //...
+  else {
+    
+  }
+*/
+
+  switch(option){
+    case 1:
+      cout << "You have one dog" << endl;
+      break;
+    case 2:
+      cout << "You have two cats" << endl;
+      break;
+    case 3:
+    case 4:
+      cout << "You have some number of birds" << endl;
+      break;
+    case 5:
+      cout << "That's a lot of ducks" << endl;
+      break;
+    default:
+      cout << "These are your ideal pets" << endl;
+  }
+  
+  return 0;
+}
\ No newline at end of file
diff --git a/tostr.cpp b/tostr.cpp
new file mode 100644
index 0000000..d2ae138
--- /dev/null
+++ b/tostr.cpp
@@ -0,0 +1,13 @@
+#include <iostream>
+#include <string>
+using namespace std;
+
+int main(){
+  int thing = 300;
+  char c = 'a';
+  double d = 3.14;
+
+  cout << to_string(thing) + to_string(c) + to_string(d) << endl;
+
+  return 0;
+}
\ No newline at end of file
diff --git a/whileRef.cpp b/whileRef.cpp
new file mode 100644
index 0000000..c25dc7e
--- /dev/null
+++ b/whileRef.cpp
@@ -0,0 +1,35 @@
+#include <iostream>
+using namespace std;
+
+// should run a while loop collecting values
+// and return the sum of those values
+// *and* put the number of values read in
+// into the reference variable numberOfValues
+// loop should keep going until user enters
+// something < 0
+double averageRef(int &numberOfValues);
+
+int main(){
+  int numberThings = 0;
+  double sum = averageRef(numberThings);
+  double sum2 = averageRef(numberThings);
+  cout << "The average is: " << sum2 / numberThings << endl;
+  return 0;
+}
+
+double averageRef(int &numberOfValues){
+  numberOfValues = 0;
+  double temp = 0;
+  double input = 0;
+  
+  cout << "Enter a number (<0 to quit): ";
+  cin >> input;
+  while(input >= 0){
+    numberOfValues++;
+    temp = temp + input;
+    cout << "Enter a number (<0 to quit): ";
+    cin >> input;
+  }
+  
+  return temp;
+}
\ No newline at end of file