PrintRange

Lets you input two numbers and prints the range in between. Ascending or descending.

Two integers are read from standard input, and every integer from the first to the second is printed, inclusive, one per line:

• ascending when the first number is smaller than the second,
• descending when the first number is larger than the second,
• the number by itself when the two are equal.

The whole program is a single file, printRange.cpp.

Build

make

The binary is written to printRange in the repository root. The Makefile records the build that everything else in this repository assumes:

g++ -std=c++17 -Wall -Wextra -o printRange printRange.cpp

make clean removes the binary. The compiled artifact is covered by .gitignore and is never committed.

Run

A prompt is printed for each of the two numbers and each number is read from standard input, so running the binary with a terminal attached makes it wait for input rather than print anything useful on its own. Input is supplied by piping it in:

printf '%s\n' 1 5 | ./printRange

The printf '%s\n' <first> <last> form is used rather than printf '<first>\n<last>\n' because a negative endpoint written the second way is parsed by printf as an option.

The source contains no input validation.

Example

Ascending:

$ printf '%s\n' 1 5 | ./printRange
What is the first number in the range?
What is the last number in the range?
1
2
3
4
5

Descending:

$ printf '%s\n' 5 1 | ./printRange
What is the first number in the range?
What is the last number in the range?
5
4
3
2
1

Equal endpoints:

$ printf '%s\n' 3 3 | ./printRange
What is the first number in the range?
What is the last number in the range?
3

Crossing zero:

$ printf '%s\n' -2 2 | ./printRange
What is the first number in the range?
What is the last number in the range?
-2
-1
0
1
2

Both prompts are printed on standard output ahead of the range, so the first two lines of every session are prompts. A wide range is therefore counted with the prompts dropped — 1 through 100 inclusive leaves 100 lines:

$ printf '%s\n' 1 100 | ./printRange | tail -n +3 | wc -l
100

Continuous integration

The build workflow in .github/workflows/build.yml builds the program with make on every push to master and on every pull request, then checks the output of each branch above against a literal expected block, the line count of the 1-through-100 range, and that make clean removes the binary.

License

Stephenson Software Non-Commercial License. See LICENSE.