correctcppis_odd

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Correct C++ chapter 'is odd'.

Goals

• Respond to exceptions

Prerequisites

• Understand how this course works
• Have written a correct 'Show CLI arguments' program

Exercise

Write a command-line interface (CLI) program that determines if its argument is an odd number.

If there are more arguments supplied, ignore the ones beyond the first

Call to is_odd	Output	Exit status
./is_odd	Any	1
./is_odd 1	true (with newline)	0
./is_odd 2	false (with newline)	0
./is_odd nonsense	Any	1
./is_odd 12345678901234567890	Any	1
./is_odd 2 1	false (with newline)	0

With 'Any' output, you can choose to:

• inform the user, for example: 'Error: must supply one argument'
• give no ouput at all: the exit status of 1 indicates that the program ended with an error

This is the code you start with:

main(argc, argv)
{
  //Your code here
}

• Use std::stoi to convert a std::string to an int
• std::stoi properly [2] throws an exception if the std::string cannot be converted to an integer:
  • when the std::string is a word, like nonsense
  • when the std::string is a number too big to be an integer, like 12345678901234567890
• Use try and catch to respond to the exception thrown by std::stoi
• Avoid std::endl [1]
• catch the exception by reference [3]
• You can have multiple catch clauses per try
• Use const to define objects with values that do not change after construction [4]

External links

• Video how to do this chapter (mp4)

References

• [1] C++ Core Guidelines: SL.io.50: Avoid endl
• [2] C++ Core Guidelines: E.2: Throw an exception to signal that a function can't perform its assigned task
• [3] C++ Core Guidelines: E.15: Catch exceptions from a hierarchy by reference
• [4] C++ Core Guidelines: Con.4: Use const to define objects with values that do not change after construction