Chapter 25 // Exercise 9 - Principles & Practice Using C++

In this exercise I am using Visual Studio 2019 and a modified version of the std_lib_facilities header found here.

Chapter 25 // Exercise 9

Without using any standard headers (such as <limits>) or documentation, compute the number of bits in

an int and determine whether char is signed or unsigned on your implementation.

Github: https://github.com/l-paz91/principles-practice/blob/master/Chapter%2025/Exercise%209

So to print the number of bits in an int we know that sizeof() will return us the number of bytes in a type so you can just multiply that by 8. I don't think this is cheating as sizeof is a keyword in C++ and doesn't require any standard headers to be used. 

For the second part, I used the example from page 964. It shows that char is default signed on my machine.

Chapter 25 // Exercise 8 - Principles & Practice Using C++

In this exercise I am using Visual Studio 2019 and a modified version of the std_lib_facilities header found here.

Chapter 25 // Exercise 8

Write out the numerical values of each character on your keyboard.

Github: https://github.com/l-paz91/principles-practice/blob/master/Chapter%2025/Exercise%208

I cheated and just printed out all the ascii characters in a for loop as they're all on my keyboard anyway.

Chapter 25 // Exercise 7 - Principles & Practice Using C++

In this exercise I am using Visual Studio 2019 and a modified version of the std_lib_facilities header found here.

Chapter 25 // Exercise 7

Write out the hexadecimal values from 0 to 400; write out the hexadecimal values from -200 to 200.

Github: https://github.com/l-paz91/principles-practice/blob/master/Chapter%2025/Exercise%207

After the last exercise I honestly thought that this would trigger an infinite loop or something because Bjarne has that type of humour.

Chapter 25 // Exercise 5, 6 - Principles & Practice Using C++

In this exercise I am using Visual Studio 2019 and a modified version of the std_lib_facilities header found here.

Chapter 25 // Exercise 5

Write an infinite loop. Execute it.

Github: https://github.com/l-paz91/principles-practice/blob/master/Chapter%2025/Exercise%205

Simple enough.

Chapter 25 // Exercise 6

Write an infinite loop that is hard to recognise as an infinite loop. A loop that isn't really infinite because

it terminates after completely consuming some resource is acceptable.

Github: https://github.com/l-paz91/principles-practice/blob/master/Chapter%2025/Exercise%206

For this one I immediately though of a for loop going backwards but checking if the index was >= 0 (I'm not proud to say I've done this before...). However, Visual Studio is very smart these days and will give you an intellisense warning that the loop is infinite.

It also does the same for the old if(bool = false). I even googled for one but VS even recognised that as infinite. The best way to do it would be to just allocate memory in a recursive function.

Chapter 25 // Exercise 4 - Principles & Practice Using C++

In this exercise I am using Visual Studio 2019 and a modified version of the std_lib_facilities header found here.

Chapter 25 // Exercise 4

Add the bitwise logical operators &, |, ^, and ~ to the calculator from chapter 7.

Github: https://github.com/l-paz91/principles-practice/tree/master/Chapter%2025/Exercise%204

Just when you thought it was safe, chapter 7 returns. I last touched that code 3 years ago now according to GitHub. I remember absolutely hating tokens and token streams because I thought they were some weird special type...it's just a class that gets characters from the cin buffer lol. I really love going back to old exercises as it makes me realise that I have learnt something after all.

I decided to go with the finished code from exercise 9:

https://github.com/l-paz91/principles-practice/blob/master/Chapter%207/Exercise%209

And started by cleaning it up and putting it into seperate files. Then I added the bitwise operators  to my enum of symbols.

Now, as per the rules of the calculator, &, | and ^ are all expressions as they need primary's to operate on. However ~ is a prefix and can be used by itself so that makes it a primary. The main problem though is that you can't use (or shouldn't be using) bitwise operators on doubles as they're made up of 3 parts and our Tokens store all values as doubles.

To get round this I just cast everything to an int and then perform the operations but it prints a warning if the double wasn't safely converted to a float using std::modf();

I also made it so NOT requires parenthesis around the expression so you can do things like ~(5+4+sqrt(25)).