While this book has a small number of typographic errors, it's representative of period programming in the later 1970s and early 1980s. It illustrates stepwise refinement of a simple compiler throughout the text. It might seem silly to some to use the '+' and '=' in the title, but it also influenced quite a few important papers subsequently and gets us away from the restrictive ASCII character set.
It was briefly required reading when I was on the Pascal Standards Committee. It's an obsolete language in some ways, but it's a shorter text and in a higher level language (named PL/0)) than Donald Knuth's Art of Computer Programming, Volume 1: Fundamental Algorithms (uses MIX/MMIX) which more programmers keep as a reference than read.
Wirth importantly points out in the start the trade offs and interchange between data structures and their algorithms, and very important: the reverse (it must be explicitly stated) algorithms and THEIR data structures. It's not all about sorting.
Lots of folks in my age group like to dismiss older books. Whether that's because the language(s) of choice are no longer popular, or they incorrectly assume that because it was written before they were born its prehistoric. However, this book more than other resource on topic helped me, "get" advanced data structures. It does a brilliant job of demystifying them. Though the language is dated in the author uses, "he" when referring to the reader and some of the illustrations are borderline anti-semitic which is a bit cringeworthy. Never the less its a proper classic.
This is a classic book about basic algorithms and data structures. It's a must have book for understanding behind-the-scenes logic of standard libraries in modern programming languages. Though author could have given more alive examples. The style is a bit too formal as for me.
Incredibly modern read. It is clearly visible that this book inspired modern CS books on the same subject. Personally, I found it very interesting that Wirth (who I knew as the creator of Pascal) decides here to start from types and in particular from enumerative types. It seems that to him the modeling aspects of programming were central to discussing CS topics. I also found interesting to see that Wirth considers his readers as fluent in mathematical topics such as algebra, number theory, and in general that probably matched the situation of the 1970's were people learning about Computer Science came mostly with a strong math background.
A final node: many of the data structures and algorithms discussed in the book are central to CS today as they were at the time the book came out, but I have to say that Wirth has a terrific way to introduce and motivate the need for these structures and algorithms, and in most cases they are much clearer than in any book I used when I studied CS in the 90s :)
A good introduction to some simple algorithms, but perhaps a bit out-of-date. I also read the 2nd edition in which all the program examples are in Modula-2 which I had never heard of except in this book (it is the successor to Pascal, but it seems it didn't catch on)