diff --git a/1.cpp b/1.cpp
index 190c209..5855efb 100644
--- a/1.cpp
+++ b/1.cpp
@@ -15,11 +15,14 @@ class vector :public container {
 
 	int call_num;
 public:
-	explicit vector(int l) :len(l),size(1 * 100){
+	explicit vector(int l) :len(l),container(100){
 		p = new float();
 	}
+
+    explicit vector(const container c): container{c}
+    {}
 	int len;
-	int& getlen() const {
+	int& getlen(){
 		call_num ++;
 		return len;
 	}
@@ -29,12 +32,12 @@ class vector :public container {
 int main() {
 
 	container c1(100);
-	vector v1 = c1;
+	vector v1{c1};
 	container& r1 = v1;
 	container c2 = 100;
-	c2.getsize() = 20;
+	c2.getsize();
 	cout << c2.getsize();
-	vector v2 = 100;
-	v2.getlen = 40;
+	vector v2(100);
+	v2.getlen();
 	cout << v2.getlen();
 }
\ No newline at end of file
diff --git a/2.cpp b/2.cpp
index 6a27746..8de7df1 100644
--- a/2.cpp
+++ b/2.cpp
@@ -5,23 +5,20 @@ using namespace std;
 
 // count all the specific char in the whole array of strings
 int countAllSpecificChars(string sArr[], int arrLength, char specificChar) {
-    int count;
-    for (int i = 0; i <= arrLength; ++i)
-        for (int j = 0; j <= sArr[i].size(); ++j)
+    int count = 0;
+    for (int i = 0; i < arrLength; ++i)
+        for (int j = 0; j < sArr[i].size(); ++j)
             // if the jth char of the string is the specific char
-            if (sArr[i][j] = specificChar)
+            if (sArr[i][j] == specificChar)
                 count++;
     return count;
 }
 
 int main() {
-    string sArr[4] = {
-            "I am",
-            "in",
-            "ap",
-            "class"
-    };
+    string sArr[4] = {"I am","in","ap","class"};
     char findIt;
     cin >> findIt;
     cout << countAllSpecificChars(sArr, 4, findIt);
-}
\ No newline at end of file
+}
+
+// return the number of occurence of char findIt in the sArr 
\ No newline at end of file
diff --git a/3.cpp b/3.cpp
index c8732ef..845db37 100644
--- a/3.cpp
+++ b/3.cpp
@@ -9,17 +9,25 @@ struct alfa {
 	long long x;
 	alfaptr next;
 };
+
 alfaptr rear = NULL, front = NULL;
+
+
 void push(int x)
 {
 	alfaptr node;
 	node = (alfaptr)malloc(sizeof(struct alfa));
 	node->x = x;
 	if (!front)
+	{
 		front = node;
-	else {
+		front->next = NULL;
+	}
+	else 
+	{
 		rear->next = node;
 		rear = node;
+		rear->next = NULL;
 	}
 }
 
@@ -31,6 +39,7 @@ void pop()
 	else
 	{
 		node = front->next;
+		delete front;
 		front = node;
 	}
 }
@@ -39,18 +48,24 @@ void search(int x)
 	alfaptr node = front;
 	int counter = 0;
 	while (node)
+	{
 		if (node->x == x)
+		{
 			printf("%d", counter);
-		else {
-			printf("ERROR2");
-			break;
-		}
+			return;
+		}		
 		node = node->next;
+	}
+	
+	printf("ERROR2");
+	
+		
 }
 
 void rpop() {//pop last element
+	
 	alfaptr node = front;
-	while (node)
+	while (node->next->next)
 		node = node->next;
 	free(rear);
 	rear = node;
@@ -66,9 +81,13 @@ void set()
 int size()
 {
 	alfaptr node = front;
-	int count;
+	int count = 0;
 	while (node)
-		count++;node = node->next;
+	{
+		count++;
+		node = node->next;
+	}
+	
 	return count;
 }
 
@@ -88,16 +107,20 @@ int average()
 {
 
 	alfaptr node = front;
-	int sum = 0, count;
+	int sum = 0, count = 0;
 	while (node) {
 		sum += node->x;
 		count++;
 		node = node->next;
 	}
+	if(count == 0)
+	{
+		return 0;
+	}
 	return sum / count;
 }
 
-void main()
+int main()
 {
 	int cmd;
 	long long int x;
diff --git a/4.cpp b/4.cpp
index a9a32f2..9f3f0fd 100644
--- a/4.cpp
+++ b/4.cpp
@@ -6,4 +6,6 @@ int main()
     float *ptr2 = ptr1 + 3;
     printf("%f", *ptr2 - *ptr1);
     return 0;
-}
\ No newline at end of file
+}
+
+// print 90.5 - 12.5 which is 78.000000
\ No newline at end of file
diff --git a/5.cpp b/5.cpp
index e9a1737..33ab105 100644
--- a/5.cpp
+++ b/5.cpp
@@ -1,10 +1,11 @@
 #include<stdio.h>
 int main()
 {
-    int arr[] = { 10, 20, 30, 40, 50, 60 };
+    int arr[] = { 10, 20, 30, 40, 50, 60 }; // 5
     int *ptr1 = arr;
     int *ptr2 = arr + 5;
     printf("%d\n", (*ptr2 - *ptr1));
     printf("%c", (char)(*ptr2 - *ptr1));
     return 0;
-}
\ No newline at end of file
+}
+// print (60 - 10) and character ('2')
\ No newline at end of file
diff --git a/6.cpp b/6.cpp
index bb721c3..25cb007 100644
--- a/6.cpp
+++ b/6.cpp
@@ -9,3 +9,5 @@ int main()
 	printf("%d\n", a);
 	return 0;
 }
+
+// print 513
diff --git a/7.cpp b/7.cpp
index 7b065a0..84495bd 100644
--- a/7.cpp
+++ b/7.cpp
@@ -3,8 +3,8 @@ int main()
 {
 	int arr[] = { 1, 2, 3, 4, 5 };
 	int *p = arr;
-	++*p;
-	p += 2;
-	printf("%d", *p);
+	++*p; // 1++ -> 2 (first arr element)
+	p += 2; // go to index 2
+	printf("%d", *p); // print 3
 	return 0;
 }
\ No newline at end of file
diff --git a/8.cpp b/8.cpp
index 76b870c..4aaac2d 100644
--- a/8.cpp
+++ b/8.cpp
@@ -11,3 +11,5 @@ int main() {
 
 	
 }
+
+// print "Be WooW"