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# INTRODUCTION TO PROGRAMMING

I am collating my study notes as part of my education into Computer Programming. In an attempt to increase and improce my own learning, and to help others also (learn by teaching) I will be sharing my notes, as neatly presented as possible, for others to follow along with if they so wish. This is Lesson 3's notes.


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**EARLIER LESSONS**

[Lesson 1 Notes](https://steemit.com/education/@humate/introduction-to-computer-programming)
[Lesson 2 Notes](https://steemit.com/education/@humate/introduction-to-computer-programming-part-2)

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### INTRODUCTION TO COMPUTER PROGRAMMING – STUDY NOTES

**LESSON 3**


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**OPERATORS**

LINK: [Operators](https://en.wikipedia.org/wiki/Operator_(computer_programming))

 Operators allow you to operate on an element of the program.

 - **Assignment**

> `=`
> This means to apply the value of. For example x = y means to apply the value of x to y. It is not the same meaning as standard mathematics where it means equal to.

 - **Arithmetic Operators**

> `+`Addition 
> `-`Subtraction
> `*`Multiplication
> `/`Division
> `%`Modulo

 - Modulo = remainder of a division operation.

>Example 143 / 3 = 47.66 (standard division) but if you take only the whole numbers, then the modulo of that operation is 143 / 3 = 47, WITH a remainder of 2. In other words, 47 * 3 = 141 and the difference between 143 and 141 is 2 (This is the modulo, or the remainder). There is a need for such an operator within programming languages.

- **Compound Operators**

> `+=` : x+=y is the same as saying x=x+y
> `-+` : x-=y is the same as saying x=x-y
> `*+`  : x*=y is the same as saying x=x*y
> `/=` : x/=y is the same as saying x=x/y
> `%=` : x%=y is the same as saying x=x%y

This allows for a slightly shorter way of writing out these operators.

- **Unary Operators**

> `++` : `X++` is the same as saying `x=x+1` (used a lot in loops)
> `--`   : `X--` is the same as saying `x=x-1` (used a lot in loops)
> `!`    : Means NOT. 
> Example : `x=true`, then `!x` would then be false (ie - NOT true)

- **Prefix Operator vs Suffix Operator**

LINK: [Increment and Decrement Operators](https://en.wikipedia.org/wiki/Increment_and_decrement_operators)

When the ++ or -- is set as a prefix as opposed to a suffix like earlier described, then the value of the variable that it relates to is handled differently. The variable is increased FIRST then assigned to the new variable.

> **Prefix** Example: 
> `x = 3`
> `y = ++x`
> In this example x is assigned (=) the value of 3, and then because of the PREFIX in the second line, x is increased by 1 to 4 (++x) BEFORE y is assigned that value. Now both x and y have the value of 4.

The suffix example would create a different answer. 

> **Suffix** Example
> `x = 3`
> `y = x++`
> In this example x is assigned (=) the value of 3, and then because of the SUFFIX in the second line, x is increased by 1 to 4 (x++) AFTER y is assigned that value. So y is assigned the value of x which is 3, THEN x is increased by 1 to 4.

This seemingly minor but significant difference can lead to logical errors in your program if you apply the wrong use of suffix/prefix. 
 
Suffix = value is assigned first before it is increased.
Prefix = value is increased first before it is assigned.

- **Relational/Comparison Operator**

Used to compare 2 values.
Will always evaluate to a Boolean value (TRUE or FALSE).

> `==` : equal to
> `!=`  : not equal to
> `>`   : greater than
> `<`   : less than
> `>=` : greater than or equal to
> `<=` : less than or equal to

**- Logical Operator**

Used to tell the computer to do an operation when certain conditions or mix of conditions are met. Such as condition 1 AND condition 2; condition 1 OR condition 2. Also the NOT operator.

> `!`  : NOT : 
> `&&` : AND : True only when both conditions are true.
> `||` : OR  : True if one or the other is true.

- **Operator Precedence**

There is an order to which operators are evaluated. There is an order of importance. 
All the languages use the same precedence.


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LINK: [C++ Example](http://www.cplusplus.com/doc/tutorial/operators/)
LINK: [JavaScript Example](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Expressions_and_Operators) 




![enter image description here](https://s19.postimg.org/vygaw2ukz/william-bout-264826_l.jpg)


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**FURTHER DATA**

[cpp.sh](http://cpp.sh/) - C++ shell website
Scratchpad - Shift + F4 on Firefox - Javascript shell
[Dev C++](https://sourceforge.net/projects/orwelldevcpp/) - A free, portable, fast and simple C/C++ IDE
[Code::Blocks](http://www.codeblocks.org/) - A free C, C++ and Fortran IDE
[Ideone](https://ideone.com/) - an online compiler and debugging tool which allows youto compile source code and execute it online in more than 60 programming languages.

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**My Posts**

[Introduction From a Newbie Programmer](https://steemit.com/introduceyourself/@humate/introduction-from-a-newbie-programmer).

[Introduction to Computer Programming - part 1](https://steemit.com/education/@humate/introduction-to-computer-programming) (Lesson 1)

[Introduction to Computer Programming - part 2](https://steemit.com/education/@humate/introduction-to-computer-programming-part-2) (Lesson 2)


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Images from [unsplash.com](https://unsplash.com/).

I welcome new followers, and thank you for your upvotes and comments.

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