Currently taking part in a study group for the abovementioned book.
I was curious to see if I could write a simple filter. Using cppreference.com for information on the C++ standard libraries, I came up with this, saved into the file irb-filter.cpp:-
/*
The most basic filter ever, copies cin to cout.
Ian Bruntlett 5th May 2024
To check for memory errors, do this:
$ valgrind --tool=memcheck ./irb-filter <rose.txt
To see cache performance, do this:
$ valgrind --tool=cachegrind ./irb-filter <rose.txt
See valgrind.org for more info on valgrind
*/
#include <iostream>
#include <string>
int main()
{
std::string line;
//std::cout << "line.capacity() = " << line.capacity() << '\n';
//line.reserve(200); // assume lines typically 200 characters or less
while ( std::getline(std::cin,line) )
std::cout << line << '\n';
//std::cout << line.capacity() << " length " << line.length() << ' ' << line << '\n';
}
I've left in some comments in case the reader want to delve a bit deeper. I've also left in some commented bits of code I used to check my understanding of what is happening when the code is being run.
I compiled the code with my makefile, which in turn ran this command:
g++ -g -Wall -Wshadow -Wconversion -std=c++23 -Wl,-Map=irb-filter.map irb-filter.cpp -o irb-filter
Here are the contents of rose.txt:
The Sick Rose
By William Blake
O Rose thou art sick.
The invisible worm,
That flies in the night
In the howling storm:
Has found out thy bed
Of crimson joy:
And his dark secret love
Does thy life destroy.