I develop in Javascript, Python, PHP and Ruby. By far Ruby is my favorite programming language.

Together let start a journey and revisit our Ruby foundations.

Each post will include some theory but also exercise and solution.

If you have any questions/comments or your are new and need help, you can comment below or send me a message.

Numbers Type in Ruby

In Ruby the two numbers primary type are Integer and Float.

# Integerage = 27# Floatprice = 79.99

Attention: In Ruby manipulating integers always end up with an integer

number = 1 / 100 # 0

Why this division return 0? Because both numbers are integer and Ruby assumed that you would want a rounded value, so it rounded it to the nearest whole number, which is 0 in this case.

Ok but what can I get the right value with decimal? Yes just use a float in the equation

number = 1.0 / 100 # 0.01

Arithmetic Order of Operations

If we try to run this code what will be the value? In which order the operation will be run?

In Ruby the order of operation is

• Parentheses
• Exponent
• Multiplication
• Division
• Addition
• Subtraction

A old trick to remember this order is to take the first letter of each item that give the word PEMDAS

Let's do example:

result = 100**2 + 20 - 200 / (7 - 2) + 150 + 2 * 100# 10330

Here the order of operation to make that result possible

# 1. Parentheses(7-2) = 5100**2 + 20 - 200 / 5 + 150 + 2 * 100# 2. Exponent100**2 = 1000010000 + 20 - 200 / 5 + 150 + 2 * 100# 3. Multiplication2 * 100 = 20010000 + 20 - 200 / 5 + 150 + 200# 4. Division200 / 5 = 4010000 + 20 - 40 + 150 + 200# 5. Final Addition and Subtraction10000 + 20 - 40 + 150 + 200 = 10330

Numbers methods

Here are some numbers manipulation methods

# Roundnumber.round 2.68  # 3# Round downnumber.floor 2.68  # 2# Round upnumber.ceil 2.68   # 3# Next2.next  # 3# Is number event ?puts 2.even?  # true# Is number odd ?puts 2.odd?   # false# Generate a random numberrandom_number = rand(1..100)

Exercice

Create a little program that:

1. Generate a random number between 1.0 and 100. That will generate a float number.

2. Use the round method to round your random number.

3. Create an arithmetic operation using all the PEMDAS item and try figure out the result without looking at Ruby result.

Solution

number1 = rand(1.0..100).round# 74# Example onlynumber2 = 2**4 + 50 * (10 + 20) / 4# 391

Conclusion

That's it for today. The journey just started, stay tune for the next post very soon. (later today or tomorrow)

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