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https://github.com/adrianhenry15/cs50-readability

HarvardX CS50's Introduction To Computer Science
https://github.com/adrianhenry15/cs50-readability

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HarvardX CS50's Introduction To Computer Science

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# HarvardX CS50's Introduction To Computer Science



## Week 2 Problem Set: Readability

For this problem, you’ll implement a program that calculates the approximate grade level needed to comprehend some text, per the below.



```

$ ./readability

Text: Congratulations! Today is your day. You're off to Great Places! You're off and away!

Grade 3

```



### Background



According to Scholastic, E.B. White’s Charlotte’s Web is between a second- and fourth-grade reading level, and Lois Lowry’s The Giver is between an eighth- and twelfth-grade reading level. What does it mean, though, for a book to be at a particular reading level?



Well, in many cases, a human expert might read a book and make a decision on the grade (i.e., year in school) for which they think the book is most appropriate. But an algorithm could likely figure that out too!



So what sorts of traits are characteristic of higher reading levels? Well, longer words probably correlate with higher reading levels. Likewise, longer sentences probably correlate with higher reading levels, too.



A number of “readability tests” have been developed over the years that define formulas for computing the reading level of a text. One such readability test is the Coleman-Liau index. The Coleman-Liau index of a text is designed to output that (U.S.) grade level that is needed to understand some text. The formula is

```

index = 0.0588 * L - 0.296 * S - 15.8

```

where `L` is the average number of letters per 100 words in the text, and `S` is the average number of sentences per 100 words in the text.



Let’s write a program called `readability` that takes a text and determines its reading level. For example, if user types in a line of text from Dr. Seuss, the program should behave as follows:



```

$ ./readability

Text: Congratulations! Today is your day. You're off to Great Places! You're off and away!

Grade 3

```



The text the user inputted has 65 letters, 4 sentences, and 14 words. 65 letters per 14 words is an average of about 464.29 letters per 100 words (because 65 / 14 * 100 = 464.29). And 4 sentences per 14 words is an average of about 28.57 sentences per 100 words (because 4 / 14 * 100 = 28.57). Plugged into the Coleman-Liau formula, and rounded to the nearest integer, we get an answer of 3 (because 0.0588 * 464.29 - 0.296 * 28.57 - 15.8 = 3): so this passage is at a third-grade reading level.



Let’s try another one:

```

$ ./readability

Text: Harry Potter was a highly unusual boy in many ways. For one thing, he hated the summer holidays more than any other time of year. For another, he really wanted to do his homework, but was forced to do it in secret, in the dead of the night. And he also happened to be a wizard.

Grade 5

```

This text has 214 letters, 4 sentences, and 56 words. That comes out to about 382.14 letters per 100 words, and 7.14 sentences per 100 words. Plugged into the Coleman-Liau formula, we get a fifth-grade reading level.



As the average number of letters and words per sentence increases, the Coleman-Liau index gives the text a higher reading level. If you were to take this paragraph, for instance, which has longer words and sentences than either of the prior two examples, the formula would give the text an twelfth-grade reading level.

```

$ ./readability

Text: As the average number of letters and words per sentence increases, the Coleman-Liau index gives the text a higher reading level. If you were to take this paragraph, for instance, which has longer words and sentences than either of the prior two examples, the formula would give the text an twelfth-grade reading level.

Grade 12

```



### Getting Started



1. Make sure you have a compiler for C programs. Some popular compilers include GCC, Clang, and Microsoft Visual C++.

2. Clone the repo.

3. `cd` into the respective directory.

4. Compile the code `gcc -o caesar caesar.c`.

5. Start the program `./caesar`