C++

Type inference in C++

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The new C++0x standard provides support for type inference. The auto keyword that was doing nothing in C++ was given a new meaning: a placeholder for a type inferred by the compiler. For those familiar with C#’s var keyword, this is basically the same. Here is a comparison between auto in C++ and var in … Read more

Evaluate Expressions – Part 4: Evaluate the Abstract Syntax Tree

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Evaluate Expressions – Part 1: The Approaches Evaluate Expressions – Part 2: Parse the Expression Evaluate Expressions – Part 3: Building the Abstract Syntax Tree Evaluate Expressions – Part 4: Evaluate the Abstract Syntax Tree So far we have managed to parse the text representing an expression and build an abstract syntax tree. The only … Read more

Evaluating Expressions – Part 3: Building the AST

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In my previous post we’ve parsed an exception verifying whether it’s correct or not syntactically. But we still have to evaluate it. To be able to do that we’ll have to build an abstract syntax tree. This can be done by modifying the previous code and inserting semantic action. That means we do something more … Read more

Evaluating Expressions – Part 2: Parse the Expression

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In my previous post I have provided some background theory for evaluating expressions with abstract syntax trees. As I was mentioning, the first step towards this goal is to parse the expression, make sure it is correct syntactically. This is what I’ll show you in this post. Having the grammar defined, we’ll make one function … Read more

Evaluating Expressions – Part 1: The Approaches

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I was discussing a few days ago about evaluating expressions and I decided to explain how you can build an evaluator. I will do this in a series of posts, getting one step more in each post. I will use C++, but the approaches are the same regardless the language. Let’s consider this expression: 1+2*3. … Read more

Writing UTF-8 files in C++

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Let’s say you need to write an XML file with this content: < ?xml version=”1.0″ encoding=”UTF-8″? > < root description=”this is a naïve example” > < /root > How do we write that in C++? At a first glance, you could be tempted to write it like this: #include < fstream > int main() { … Read more

Output Formatting with std::copy

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I had to do some output formatting in C++ for showing the content of a buffer. Take for instance this buffer: unsigned char buffer [] = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F }; I wanted the output to be like this: 0x00, 0x01, 0x02, … Read more