Piping input into a c++ program to debug in Visual Studio

Question

this has probably been asked before, but I haven't been able to find any answers so far. I'm trying to start my program up with multi-line input, I.E. something I don't want to type in the command line every time (as I'd probably make a mistake). I looked into the command line arguments and I pasted my input in there, but it interpreted it as every line being a command.

Input in case it helps:

8
c j i b s x k j
t a o a v y z l
x r t s w o n m
z y x e n s p r
l l o b s t e r
t g x a a a a a
j p e l a k e k
t r s l j e e e
cat
test
baseball
bake
paste
lobster
stake
zen
locks
rake
gel
slack
jar
dinosaur
0

Solution 1

Put your data in a file then go to the project properties in Visual Studio and select the "Debugging" category.

In the "Command Arguments" property type:

< "path/to/the/file"

Now that file will be fed to the program via standard input when the debugger is launched or when you launch the program within Visual Studio (but without the debugger) using Ctrl-F5.

You can use VS macros to specify the project directory, etc. if you want the test file to move along with the project.

Solution 2

You may save your input as a file.(like "intput.txt"). Then call

freopen("intput.txt", "r", stdin);
//code to read from stdin.
fclose(stdin);

Comments

[Joe]

Additionally I usually just add the data file as a regular file in the project, and mark it 'exclude from build'. Then you can just set the arguments in the debugger to '< FileIMade.txt'. Make sure wording directory is set to $(ProjectDir) and you are good to go and the file is available for easy editing access in the project and/or source control.

[Seng Cheong]

If I remember correctly, this isn't documented but works! Its particularly surprising because < is normally handled by the shell, which doesn't exist in this case.

[Michael Burr]

One thing to be aware of is that the debugger redirection was broken in VS2008: stackoverflow.com/a/3122074/12711 It's not clear exactly which versions of 2008 it's broken in - it's working for me today in VS 2008 SP1 on Win7 x64, but comments in the bug report indicates that for some people VS2008 SP1 doesn't fix it.

[Ivan Gonzalez]

This is so good for debuggers who don't allow piping like vscode