C Functions

Today, I am going to discuss about "Functions".

Functions are a group of statements that is created to perform a special task and returns a value as its result.
Example: The main() function.


From the above definition, you can get:

-Function is a group of statements.

-Function performs special tasks.
 Example: The factorial function is used to calculate the factorial of a given number.

-Function returns a value.
 Please note this: Functions return one value only no matter how many arguments it has as its input(s).


So, how do we create a function?

Use this syntax:

return_type function_name (data_type var1, data_type var2, ....){
 //statement1;
 //statement2;
 //...
return data
}

Let's go straight to creating our own function.
I would like to show you how to create a factorial function by using iteration rather than recursion.

First of all, I need to explain what factorial is and how it works.

n factorial, denoted by n!, is the factorial of n which equals to n * (n-1) * (n-2) * ... * 3 * 2 * 1.

So, 5! = 5*4*3*2*1 = 120 and 7! = 7*6*5*4*3*2*1 = 5040.

If you analyze it thoroughly, you will see that 5! can also be 1*2*3*4*5 and it still equals to 120. The same thing works for 7! too.

Therefore, we can conclude that:

n! = 1 * 2 * 3 *.... * (n-2) * (n-1) * n

We have learned about the For Loop before, now we are going to put it into use.


How are we going to calculate the factorial of n?

It's simple, all we have to do is loop from 1 to n, multiply each values respectively, store it in a variable, then return the result.


The code would be like this:

int fact(int x){
 int i=1;
 int result=1;
 for(i=1; i<=x; i++){
   result = result * i;
 }
 return result;
}

Explanation:
Integer x is the input, Integer i is the loop counter, Integer result is the value that will be returned as the result of the operation performed.

Let me simulate the flow of this program.

Let the input (x) be 5. The program will loop for 5 times.

Loop 1 :
i = 1, result = 1*1 = 1

Loop 2 :
i = 2, result = 1*2 = 2

Loop 3 :
i = 3, result = 2*3 = 6

Loop 4 :
i = 4, result = 6*4 = 24

Loop 5 :
i  = 5, result = 24 * 5 = 120 (answer)


Assuming you want to display your result, you would want to create your main function. The whole program will look like this :

#include <stdio.h>
#include <stdlib.h>

int fact(int x){
 int i = 1;
 int result = 1;
 for(i = 1; i <= x; i++){
   result = result * i; 
 }
 return result;
}


int main(){
  printf("%d\n",fact(5)); 
  system("pause"); 
  return 0; 
}

Description of the code:
The main program prints the factorial of 5. If you want it to print the factorial of different number, you can do so by changing the 5 to another number.

Please note that he result variable is an Integer and an Integer has its limit. It will not be able to calculate the factorial of large numbers. If you wish to calculate the factorial of large numbers, you might want to change the return_type of the function.

Anyway, here's a preview of the program we have just created:

Happy Coding,
Cyber Frost

Binary Conversions

Hello Coders.

Today I would like to discuss about binary digits.
If you don't know what a binary digit is, here is a simple explanation:

A Binary Digit is a digit of number whose value is either 0 or 1.

In computer, the 0s and 1s indicate electrical signals.
1 indicates ON, 0 indicates OFF.

As we have learned in the previous post about data types,  a character has a size of 1 byte.
1 byte equals to 8 bits.

Basically a set of binary digits make up 1 byte, or 8 bits.

Examples: 1111 1111, 0000 1010, 1010 1110, etc.

What can we do with those 1s and 0s?

You can convert them to decimals, octals, and hexadecimals.
Also, you can use the AND, OR, and XOR operators to perform special conversions.

Converting Binary to Decimal 

Each digit of binary represents a decimal value which is 2ⁿ, where 0 <= n < 8 .

The leftmost digit in an 8-bit set of binary digits has the value of 2⁷ while the rightmost has the value of 2⁰. The digits in between has the value from 2⁶ to 2¹ in a left-to-right order.

Let's go right to the examples:

• 11111111 = 1*2^7 + 1*2^6 + 1*2^5 + 1*2^4 + 1*2^3 + 1*2^2 + 1*2^1 + 1*2^0 = 255
• 00000001 = 0*2^7 + 0*2^6 + 0*2^5 + 0*2^4 + 0*2^3 + 0*2^2 + 0*2^1 + 1*2^0 = 1
• 01010101 = 0*2^7 + 1*2^6 + 0*2^5 + 1*2^4 + 0*2^3 + 1*2^2 + 0*2^1 + 1*2^0 = 85
• 00110010 = 0*2^7 + 0*2^6 + 1*2^5 +1*2^4 + 0*2^3 + 0*2^2 + 1*2^1 + 0*2^0 = 50

So let's say you have sets of 3-bit binary digits:

• 111 = 1*2^2 + 1*2^1 + 1*2^0 = 7
• 010 = 0*2^2 + 1*2^1 + 0*2^0 = 2
• 000 = 0*2^2 + 0*2^1 + 0*2^0 = 0
• 100 = 1*2^2 + 0*2^1 + 0*2^0 = 4 

 Or sets of 4-bit binary digits:

• 0111 = 0*2^3 + 1*2^2 + 1*2^1 + 1*2^0 = 7
• 1010 = 1*2^3 + 0*2^2 + 1*2^1 + 0*2^0 = 10
• 0100 = 0*2^3 + 1*2^2 + 0*2^1 + 0*2^0 = 4
• 1001 = 1*2^3 + 0*2^2 + 0*2^1 + 1*2^0 = 9

 There you go. You are now capable of converting binary digits to its decimal value.

Converting Binary to Octal

In converting binary(base-2) to octal(base-8), you need to understand that octals are numbers ranging from 0-7 only. This means that 777 exists while 008 doesn't.

To convert an 8-bit binary to its octal value, you need to separate it into 3-bits at a time, starting from the right. Like this:

1111 1111 =  11 | 111 | 111

Three bits at a time? Why is there a 2-bit part then? Simple add 0 in front to make it 3-bits. Notice that 011 == 11 in binary. So, here is the digits after separation:

011 | 111 | 111

Then what?

Calculate each part, convert them to its decimal value.

011 = 2+1 = 3
111 = 4+2+1 = 7
111 = 4+2 +1 = 7

So, 11111111₍₂₎ = 377₍₈₎

Another example:
1010 1010 = 010 | 101 | 010 = 252₍₈₎

Converting Binary to Hexadecimal

Hexadecimal numbers range from 0 to F: 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F.

In order to convert to Hexadecimals(base-16), you will need to separate the bits four at a time.

Example:

1111 1111₍₂₎ = ..... ₍₁₆₎

= 1111 | 1111 

= 1*2^3 + 1*2^2 + 1*2^1 + 1*2^0 | 1*2^3 + 1*2^2 + 1*2^1 + 1*2^0

= 15 | 15

= FF₍₁₆₎

1001 1100₍₂₎ = ..... ₍₁₆₎

= 1001 | 1100
= 1*2^3 + 0*2^2 + 0*2^1 + 1*2^0 | 1*2^3 + 1*2^2 + 0*2^1 + 0*2^0
= 9 | 12
= 9C₍₁₆₎

Using the AND(&&) Operator

Here is what the AND operator does when two values are passed to it.

p	q	p AND q
1	1	1
1	0	0
0	1	0
0	0	0

Let's assume we have two sets of binary digits: 11110101 and 00110101. Using the AND operator, we will receive the result:

11110101
00110101 AND
00110101

Another example with 00001110 and 11101100.

00001110
11101100 AND
00001100

Using the OR(||) Operator

The table of OR looks like this:

p	q	p AND q
1	1	1
1	0	1
0	1	1
0	0	0

So, if your perform an OR on 11110000 and 00001111, you will get:

11110000

00001111 OR

11111111

It is similar to the AND operator, only with different rules.

Using the XOR(^) Operator

The XOR Operator is also called the Exclusive OR. Its table has values like this:

p	q	p AND q
1	1	0
1	0	1
0	1	1
0	0	0

It can be used to swap digits. Let me show you.

Let A be 00110011 and B be 01011100.

We would like to swap the value of A and B.

We can use the XOR Operator to accomplish the task, like this:

A = A ^ B

B = A ^ B

A = A ^ B

The formula can also be simplified as A^=B^=A^=B

The process looks like this:

A = 00110011

B = 01011100 XOR

A = 01101111

A = 01101111

B = 01011100 XOR

B = 00110011 ------------------- B is now A

A = 01101111

B = 00110011 XOR

A = 01011100 ------------------- A is now B

These concepts can be applied to your programming. For example you can create a swap function using the XOR operator.

Good luck trying, pals.

Regards,
Cyber Frost

The For Loop in C

The loop is one of the most critical parts of programming.
According to Wikipedia, a loop is a sequence of statements which is specified once but which may be carried out several times in succession. Read more about Loops here.

So, basically, a loop is a statement used to repeat one or more actions for a specified number of times.

There are two types of loop :

1. Finite Loop
2. Infinite Loop

When looping, in most cases, you would want to avoid infinite loops because it might crash your whole system.

There are actually several kinds of Loops in C which are the For loop, the While loop, and the Do...While Loop. But today, we are going to discuss about the For loop.


Let's go straight to the syntax of declaring a for loop:

for(initial_condition;loop_condition;increment){
//statement1
//statement2
//....
}

The initial condition is set by assigning a value to a variable, called Control Variable.
The loop condition is the condition to be checked at the start of every loop cycle. If the condition is true, continue the looping process, else, break(or stop) the process.
The increment is the value added to the Control Variable at the end of every loop cycle.
The statements within the parentheses are the statements to be executed in every cycle of the loop.


Example:

Output numbers from 1 - 10 using no more than 1 printf function.

 #include <stdio.h>
#include <stdlib.h>

int main(){
 //declaration of control variable
 int i = 0;

 //declaration of for loop
 for(i = 1; i <= 10; i++){
     printf("%d\n", i);  
    }
   
 system("Pause");  
 return 0;  
}

Magically, it works. Here is the result :

Let me explain the loop declaration part.

There is i = 1, this means, the count starts from 1.
Then, there is i <= 10, this indicates that the loop will only end after i is larger than 10. If i is still in range (1-10), the loop will continue to display i, which is incremented by 1 every cycle by using the i++ statement.

Note : You can also use +1 increment this way -> i += 1


Okay, let's mess a little with the increment part of loop now.
Let us create two loops to display odd and even numbers from 1-10, respectively.

#include <stdio.h>
#include <stdlib.h>

int main(){
 //declaration of control variable
 int i = 0;

 //declaration of for loop for odd numbers

 printf("Odd numbers:\n");
 for(i = 1; i <= 10; i += 2){
     printf("%d\n", i);  
    }

 //declaration of for loop for even numbers  
   
 printf("\nEven numbers:\n");  
 for(i = 2; i <= 10; i += 2){
     printf("%d\n", i);  
    }  
   
   
 system("Pause");  
 return 0;  
}

As you can see from the code, there are two for loops having the same increment but producing different results. If you look closely, you will find that the only difference is in the initial value of both loops. To obtain odd numbers, you start from 1 and add by 2 each loop. However, in order to display even numbers, you need to start from 2(the first even number in range) and increment it by 2 through the loop. You can see the result below:

To close this post, I would like to present you with an example of creating an infinite loop.
Despite the fact that we are doing it in purpose right now, it might happen a lot as accidents in programming later on. Here it is:

#include <stdio.h>
#include <stdlib.h>

int main(){
 //declaration of control variable
 int i = 0;

 //declaration of for loop for odd numbers

 for(i = 1; i <= 10; i--){
     printf("*");  
    }
    
   
 system("Pause");  
 return 0;  
}

 It prints the * symbol endlessly. Why? As you can see, the loop condition is i <= 10 while the loop increment is i--. This ensures that the i never reaches 10 or above(not even 2 actually).

Note: To stop the program, press Ctrl + C


Loops can be used for many occasions, you have to experiment by yourself in order to be fluent in using loops. Any questions are welcomed. Post them here as comments or send it to my email at cyberfrostprogrammer@yahoo.com.

Thank you for reading.




Happy Coding,
Cyber Frost

Arrays and Self-Pointers

Let's jump a little bit further to "Arrays and Self-Pointers".
I apologize to go directly to this part, but I do have to explain this now. I will go back to the basics later on.

First of all, let's define the meaning of an Array. An array is a group of contiguous memory location that has a predefined size as well as one data type for all its elements.

Before I can explain the terms contiguous, predefined size, and one data type, I will first show you an example of array declaration :

  data_type array_name[size] = {element-1, element-2, element-2, ... , element-size};

Just like variables, you need to initialize the elements in an Array before using it to prevent runtime errors. It is done by assigning values to each of the elements in the array using the equal sign (=) then followed by an open parenthesis and the value of element-1, element-2, and so on, then finally closing it up with a closing parenthesis.

 Now, I am going to explain about the terms.

• Contiguous

           It means every element in an Array is located next to one another in the memory depending on  their index. Why is this so important?

           With this feature of array, it is possible to do sorting, searching, and many more since you can easily loop through every element in an Array due to its elements contiguous memory location. This will be shown in an example later in the post.

• A Predefined Size

           Since an Array's memory locations for its elements need to be contiguous, it needs a proper declaration for size, so that it can allocate the space in the memory for storing the value of the elements it has.Once the size is declared, an array cannot be resized during runtime.

•  One Data Type

            An Array can only store elements of one uniform data type.
            Example : an int array can only store integer values in it.
            Why? If you refer to the previous post about variables, you can see that every data type has different sizes, so, if you store a double value into an integer array, you will absolutely get the wrong value when you use the value again, which is why you can only store values with the same data type.

Viewing The Value of An Array Element

To look at the value of an array element, you can simply use printf or any other output functions in C.

Note : An array index starts from 0, so an array[0] will have indexes of 0-9 only.

#include <stdio.h>
#include <stdlib.h>

int main(){
//Declaring an Integer Array with the size of 4
 int array[4] = {1, 3, 5, 7};
//Prints the value in index 0 of array[4]
 printf("array[0] = %d\n", array[0]);  
//Prints the value in index 1 of array[4]
 printf("array[1] = %d\n", array[1]);  
//Prints the value in index 2 of array[4]
 printf("array[2] = %d\n", array[2]);  
//Prints the value in index 3 of array[4]
 printf("array[3] = %d\n", array[3]);
/*Pausing the screen to see results,
**because dev-cpp does not freeze at the end of program
**/ 
 system("Pause");
//returns 0 to indicate successful run
 return 0;  
}

 To see how it works, just type the code into your Dev-Cpp (or other IDEs) and run.

Assigning Values to Array Elements

To assign values to an array element, you simply use this syntax:

array_name[index] = value;

 Example:

    #include <stdio.h>
    #include <stdlib.h>

    int main(){
    //Declaring an Integer Array with the size of 4
     int array[4] = {1, 3, 5, 7};
    //Prints the value in index 0 of array[4] before value changes
     printf("array[0] = %d\n", array[0]);
    //Asigns value 9 to array[0]
     array[0] = 9;
    //Prints the value in index 0 of array[4] after value changes
     printf("array[0] = %d\n", array[0]); 
    system("Pause");
    return 0;
    }

Self-Pointers

Now, we come to an interesting part of the Array data structure.

Please take note that : An array's name is  the address of its first element in memory.

Let's say you have an array of size 10.
Assuming that the address of its first element is 123, the address of its second element would be 124, and the address of its third element would be 125, and so on. How is that possible? Scroll to the Contiguous section.

Now how can we make use of that?
First, I would like to introduce Pointer to you.
A pointer is a variable that stores the memory location of another storage types(variables, arrays, etc.).
Okay, so it stores memory locations, now what?
If you assign an array's name to it, what happens?  It stores the location of the first element of the array in the memory. Then what can you do with that?
You can easily do pass-by-reference to functions, you can do self-pointing, you can also view/modify the value of an array element without actually having to access the array itself (indirection), and many more.

As an example, I will show you how to use pointers to self-point using an array.

#include <stdio.h>
#include <stdlib.h>

int main(){
//Declaring an Integer Array with the size of 4
 int array[4] = {1, 3, 5, 7};

 printf("Viewing array elements through indexes :\n");
//Prints the value in index 0 of array[4]
 printf("array[0] = %d\n", array[0]);  
//Prints the value in index 1 of array[4]
 printf("array[1] = %d\n", array[1]);  
//Prints the value in index 2 of array[4]
 printf("array[2] = %d\n", array[2]);  
//Prints the value in index 3 of array[4]
 printf("array[3] = %d\n", array[3]);
 printf("\nViewing array elements through self-pointers :\n");
 //Prints the value in location 'array'
 printf("array[0] = %d\n", *array);  
//Prints the value in location 'array+1'
 printf("array[1] = %d\n", *(array+1));  
//Prints the value in location 'array+2'
 printf("array[2] = %d\n", *(array+2));  
//Prints the value in location 'array+3'
 printf("array[3] = %d\n", *(array+3));

 system("Pause");
 return 0;  
}

You can also assign values to an array element using a self-pointer.

    #include <stdio.h>
    #include <stdlib.h>

    int main(){
    //Declaring an Integer Array with the size of 4
     int array[4] = {1, 3, 5, 7};
    //Prints the value in index 1 of array[4] before value changes
     printf("array[1] = %d\n", array[1]);
    //Asigns value 9 to array[1] using a pointer
     *(array+1) = 9;
    //Prints the value in index 1 of array[4] after value changes
     printf("array[1] = %d\n", array[1]); 
    system("Pause");
    return 0;
    }

That was just a preview on Pointers. More on next posts.
Hope it inspires you.



Happy Coding,
Cyber Frost

Variables in C

Just like any other programming languages, C also has variables.
If you do not know already, a variable is a storage location for several types of values.
There are 4 basic types of variable type specifiers in C, according to Wikipedia :

-char
-int 
-float 
-double

 
which can be combined with optional specifiers :

-signed 
-unsigned 
-short 
-long


In total, there are 28 basic data types in C. Here is the complete list along with the description: http://en.wikipedia.org/wiki/C_data_types

The syntax to declare a variable in C is simple, which is :

data_type var_name = initial_value;

Let's see how we use it in a C source code:

#include <stdio.h>
#include <stdlib.h>

int main(){
//declaring the variables
int a = 5;
int b = 2;
int c = a + b;
//printing the value of c, which is a+b, or 5+2
printf("%d",c);
//printing a new line
printf("\n");
//pausing the program to see the result
system("Pause");
return 0;
}

If you can see, I wrote several lines of words using a "//" sign in front. They are called comments. Comments will not be run by the compiler, they are only used to aid programmers to understand the source code. More about comments in the next post.

From the code you can see that I declared an Integer a with the initial value of 5 and Integer b with the initial value of 2. I then declared another Integer c with the value of a + b. Next, I print out the result, which is the value of c using printf.
You can also use other data types for different operations. Let's do division with integer and float data types for example. Here is the code :

#include <stdio.h>
#include <stdlib.h>

int main(){
//declaring the variables
float a=5;
int b=2;
float c=a/b;
//printing the value of c, which is a/b, or 5/2
printf("%f",c);
//printing a new line
printf("\n");
//pausing the program to see the result
system("Pause");
return 0;
}

The code is pretty much the same, with small modifications here and there.
If you notice, we cannot use integers as the dividend here. Why?
An Integer will always be a non-decimal number, which will give you a wrong result of the division if you declare a or c, or both, as an Integer. Ex : 5/2 = 2.

There you go. Now you can apply variables in your codes. Congratulations !
 


Happy Coding,
Cyber Frost

Basic Structure of C Programs

Every programming language has its basic structure, that is, how and where the lines of code are written.

In C, it looks like this :

#include <stdio.h>

int main(){
    //statement1;
    //statement2;
    //..........;
return 0;
}

Let's start from the top.

The #include statement is used for including a header file into your program. In this case, stdio.h.
It must precede any other lines of code in your source file.
The int is a return type specifier for the function main(). Every C program must have a main() function in order to run. Even though your program has a thousand lines of code, it will start by executing the main() function.

More about return type of main():
The main() function returns 0. which is an int as an indicator to the compiler that the program was well-executed (without error).

Then, there are these symbols, the {parentheses}, to indicate the start and the end of the main() function. Every line of code, or statement, within the parentheses must be followed by a semicolon (;).

Finally, there is the return statement, which pretty much describes its function already : to return a value from the function it represents. In this case, it is the main() function.

The End. By now you should have the basic knowledge to start writing codes in C.



Happy Coding,
Cyber Frost

Coding in C using Dev-Cpp IDE

Greetings, fellow coders.

Today, I am going to show you an open-source application which enables easy coding and compiling of C programs. It is named Dev-Cpp or Dev-C++, which can be used as an IDE(Integrated Development Environment) to code and to compile C++ as well as C programs.

You can get a free copy of it here :  http://www.bloodshed.net/dev/devcpp.html

After you downloaded and installed Dev-Cpp on your computer, run the devcpp.exe file.

After the splash screen you will see :

Simply close the Tip of the Day window and we shall continue.

At the top left of Dev-Cpp, you will see the File menu, click on it to start a new Project or Source.

Let's try to create a C source file.
Click on File>New>Source File. A new tab will open up, like this :

 

Now type in this code to the code editor:

#include <stdio.h>
#include <stdlib.h>

int main(){
 printf("Hello World\n");
 system("Pause"); 
 return 0;  
}

 Done? Now click the Execute menu and choose Compile & Run or simply press F9.
 It will then ask you to save the source file first. Just save it wherever you desire, but make sure it is in the C source files (*.c) format.
 After saving, a window will show up, looking like this :

Congratulations, you have successfully created a C program using Dev-Cpp !

On the next few posts, I will be giving tutorials on creating C programs with this user-friendly IDE.




Happy Coding,
Cyber Frost

Project Euler - Problem 11

Hello readers,
It is true that I haven't been posting for a long time. I was bothered by my university entrance preparation. Now that I managed to enter a university, which is Binus International University in Jakarta and majoring in Computer Science, I can finally post again.

I was doing a Project Euler problem earlier today.
Link to Problem 11 : http://projecteuler.net/problem=11

To solve this seemingly confusing problem, I use VB.NET.
Here is the solution.

Module Module1

    Sub Main()
        Dim list1 As String = "08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08 49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00 81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65 52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91 22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80 24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50 32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70 67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21 24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72 21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95 78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92 16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57 86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58 19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40 04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66 88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69 04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36 20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16 20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54 01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48 "

'create list to be processed later on
        Dim list2(400) As Integer
        Dim x, i As Integer
        i = 1
        For x = 0 To 399
            list2(x) = CInt(Mid(list1, i, 2))
            i = i + 3
        Next
        i = 1
        For x = 0 To 399
            If i = 20 Then
                Console.Write(list2(x))
                Console.WriteLine()
                i = 1
            ElseIf i < 20 Then
                i = i + 1
                Console.Write(list2(x) & " ")
            End If
        Next
        Console.WriteLine()

'processing stages
        Dim temp, largest, pos As Integer
        'horizontal
        For x = 0 To 395
            If x = 16 Then x = 20
            If x = 36 Then x = 40
            If x = 56 Then x = 60
            If x = 76 Then x = 80
            If x = 96 Then x = 100
            If x = 116 Then x = 120
            If x = 136 Then x = 140
            If x = 156 Then x = 160
            If x = 176 Then x = 180
            If x = 196 Then x = 200
            If x = 216 Then x = 220
            If x = 236 Then x = 240
            If x = 256 Then x = 260
            If x = 276 Then x = 280
            If x = 296 Then x = 300
            If x = 316 Then x = 320
            If x = 336 Then x = 340
            If x = 356 Then x = 360
            If x = 376 Then x = 380
            If x = 396 Then x = 400
            temp = list2(x) * list2(x + 1) * list2(x + 2) * list2(x + 3)
            If temp > largest Then
                largest = temp
                pos = x
            End If
        Next
        Console.WriteLine("Numbers(H) : " & list2(pos) & ", " & list2(pos + 1) & ", " & list2(pos + 2) & ", " & list2(pos + 3))
        Console.WriteLine("Product(H) : " & largest)


        'vertical
        temp = 0
        largest = 0
        For x = 0 To 319

            temp = list2(x) * list2(x + 20) * list2(x + 40) * list2(x + 60)
            If temp > largest Then
                largest = temp
                pos = x
            End If
        Next
        Console.WriteLine("Numbers(V) : " & list2(pos) & ", " & list2(pos + 20) & ", " & list2(pos + 40) & ", " & list2(pos + 60))
        Console.WriteLine("Product(V) : " & largest)

        'diagonal1
        temp = 0
        largest = 0
        For x = 0 To 336
            If x = 16 Then x = 20
            If x = 36 Then x = 40
            If x = 56 Then x = 60
            If x = 76 Then x = 80
            If x = 96 Then x = 100
            If x = 116 Then x = 120
            If x = 136 Then x = 140
            If x = 156 Then x = 160
            If x = 176 Then x = 180
            If x = 196 Then x = 200
            If x = 216 Then x = 220
            If x = 236 Then x = 240
            If x = 256 Then x = 260
            If x = 276 Then x = 280
            If x = 296 Then x = 300
            If x = 316 Then x = 320
            temp = list2(x) * list2(x + 11) * list2(x + 22) * list2(x + 33)
            If temp > largest Then
                largest = temp
                pos = x
            End If
        Next

        Console.WriteLine("Numbers(D1) : " & list2(pos) & ", " & list2(pos + 11) & ", " & list2(pos + 22) & ", " & list2(pos + 33))
        Console.WriteLine("Product(D1) : " & largest)



        'diagonal2
        temp = 0
        largest = 0
        For x = 396 To 60 Step -1
            If x = 379 Then x = 376
            If x = 359 Then x = 356
            If x = 339 Then x = 336
            If x = 319 Then x = 316
            If x = 299 Then x = 296
            If x = 279 Then x = 276
            If x = 259 Then x = 256
            If x = 239 Then x = 236
            If x = 219 Then x = 216
            If x = 199 Then x = 196
            If x = 179 Then x = 176
            If x = 159 Then x = 156
            If x = 139 Then x = 136
            If x = 119 Then x = 116
            If x = 99 Then x = 96
            If x = 79 Then x = 76
            If x = 59 Then x = 56
            temp = list2(x) * list2(x - 19) * list2(x - 38) * list2(x - 57)
            If temp > largest Then
                largest = temp
                pos = x
            End If
        Next
        Console.WriteLine("Numbers(D2) : " & list2(pos) & ", " & list2(pos - 19) & ", " & list2(pos - 38) & ", " & list2(pos - 57))
        Console.WriteLine("Product(D2) : " & largest)
 

    End Sub

End Module

That was the code, it consists of four major processes, which is to search for the largest product of four numbers :
1. Horizontally
2. Vertically
3. Diagonally from top left to bottom right
4. Diagonally from bottom left to top right

Running the code above, we will obtain the answer, which is 70600674.

Take your time to understand the code, no need to hurry.
I will be back with more solutions.


Happy Coding,
Cyber Frost