Using C++.
Day 1
main function
g++ source1.cpp -o program1
Paths, "/" and "." and ".." in navigating directories - absolute vs relative
data type - binary itself is meaningless unless you say what data the binary represent
declare variables (int, char, string as series of chars)
statements end with semicolon
cstdio library #include
calling a function - printf
if condition block else block (example: do something different based on argc)
for loop - 3 statements (initialiser, condition, post-loop advancement) and a code block
Homework: study "while" loop and "switch" statement
Day 2
While loop - condition and 1 code block.
Do while loop - code block then condition.
While loop = for loop with empty initialiser/advancement statements
Switch - match expression's result to case label, execute statements until break.
Switch vs if-else differences - number of times expressions are evaluated
your own function
calling with parameters copied as separate set of var values in function
classes as blueprints.
complex var data type - instances of a class all have the same set of fields
the "." field accessor (var1.func1() etc)
each instance have it's own separate memory for storing data.
Example code - fibonacci sequence.
Value overflow because not enough number of bits to represent large numbers.
Homework: implement factorial (1 to 20) calculator
in Linux, most things are case-sensitive. (A not equals a)
Day 3
factorial printer - 2 approaches:
- for-loop that goes 1 to 20 and each loop calls fact(n ) function and prints return.
- for-loop that goes 1 to 20 and multiplies once each time and print.
set initial values of vars when declaring otherwise initial values are unpredictable
factorial function - implemented in recursive way, closer to mathematical definition
stack memory
stack frame to store var values in each function call
stack overflow/crash (segfault)
base condition to stop the recursion
recursive algorithms are common - e.g. when dealing with trees
spaces in file/directory names and how to navigate - space is special in terminal
understand names chosen by yourself vs names chosen by other people for your use
creating ros package - arguments: package name, dependencies
CMakeLists.txt (.txt file can also be used with other programs)
cmake = build tool - compile many files in some defined ways
package.xml - information for ROS
compiling - carefully read and understand and seek answers to error messages
msg files - fields declaration with data type
create cpp file for a node
quick reading of code for publisher node
homework: implement message subscriber node according to ROS book