I'm having some issues with sscanf reading two values from cmd. I have this code below:
sscanf(argv[1], "%lf %lf", &m.iMin, &m.iMax);
First value assigns correctly, iMax is always set to zero. It works when used two sscanfs, though. I tried everything I found online, but unsuccesfully. I would really appreciate if someone could help me.
What input are you providing? If you are correctly putting a space between the two numbers, you will probably need to wrap the expression in double quotes when invoking
e.g
myConsoleApp.exe "100 200"
otherwise 100 and 200 are seen as 2 different args.
Related
Problem:
In powershell 5.1 I run a command, myProgram, and pass to its -itemsToProcess flag a comma separated string list (of dynamic length), $commaSeparatedList, as arguments. There are often too many characters, sometimes 125000 characters, or more, or less, in $commaSeparatedList which can cause the error shown below.
$commaSeparatedList = 'file1,file2,file3,file4 ... fileX'
myProgram -itemsToProcess $commaSeparatedList
Question:
How might I avoid the error? How might i split this into multiple calls such that the error is never thrown? The calls must be sequential too, not in parallel.
The pseudo code setup above works fine/succeeds when $commaSeparatedList is short in character length , however if its too long it crashes/fails/errors:
"the filename or extension is too long"
For example, the dynamically generated $commaSeparatedList has been 125k characters and could potentially be longer or shorter.
how might we detect and avoid the error? Perhaps somehow split it into multiple myProgram -itemsToProcess calls to avoid the error? What would that look like?
Thanks for the comments, I split the input into smaller strings and made more calls
Currently working on a project in which I must take multiple user-inputs. Because my input prompts must outline specific formatting to the user regarding how they should input their values, this makes each input prompt rather lengthy and so I've deemed it appropriate to separate each one with a line break so that it's easy to tell them apart/so that it looks nice. The last prompt is two lines long, so it would be hard to distinguish this one from the rest if they were all jumbled together rather than separated by line breaks.
I've explored the usage of fprintf() and disp(), and have found that fprintf() has some tricky behavior and sometimes will not work without including things like fflushf(), etc. Moreover, I've read that fprintf() is actually purposed for writing data to text files (from the MathWorks page, at least), and using it for another purpose is something I could definitely see my professor deducting points for if there is indeed an easier way (we are graded very harshly on script efficiency).
The disp() command seems to be more in-line with what I'm looking for, however I can't find anything on it being able to support formatting operators like \n. For now, I've resorted to replacing the usage of \n with disp(' '), however this is certainly going to result in a deduction of points.
TL;DR Is there a more efficient way to create line-breaks without using fprintf('text\n')? I'll attach a portion of my script for you to look at:
disp('i) For the following, assume Cart 1 is on the left and Cart 3 is on the right.');
disp('ii) Assume positive velocities move to the right, while negative velocities move to the left.');
prompt = '\nEnter an array of three cart masses (kg) in the form ''[M1 M2 M3]'': ';
m = input(prompt);
prompt = '\nEnter an array of three initial cart velocities (m/s) in the form ''[V1 V2 V3]'': ';
v0 = input(prompt);
disp(' ');
disp('Because the initial position of the three carts is not specified,');
prompt = 'please provide which two carts will collide first in the form ''[CartA CartB]'': ';
col_0 = input(prompt);
You can get disp to display a new line with the newline function. Putting multiple strings in square bracket will concatenate them.
disp(['Line 1' newline 'Line 2'])
You mention using fprintf, but as you found this is meant for writing to files. You can use the sprintf function to display the same formatted strings if desired.
disp(sprintf('Line 1 \nLine 2'))
In addition to Matt's solution, I figured out another way to solve my problem and wanted to post it here for anyone in the future with the same problem.
After some experimentation and some thought, I figured the most efficient way to do this (ideally) would not involve using disp() or fprintf() at all and instead would, in theory, involve actually manipulating the input prompts themselves to appear on multiple lines (rather than adding 'dummy' lines before the last line of each prompt, to make it seem as if it was all part of the prompt itself). I've been aware this whole time that simply a newline character \n will give me a linebreak in the middle of the sentence, and in theory this would work. But because the very last prompt is two lines long, simply typing one line with \n halfway through would make that line of code very long, which is what I was trying to avoid in the first place.
I realize my initial question didn't explicitly mention concatenating two (or more) strings to form an input prompt that appears on multiple lines both in the console and in the script itself, but that's essentially where I was going with this post and I apologize for any lack of clarity regarding this.
Anyways, I fixed this problem without having to use disp() or fprint() by declaring the prompt as a string array, rather than as a single string with the preceding lines of the prompt specified above it using disp() and/or fprintf() as you can see in the code I originally provided in the question. Here's how it looked before:
disp(' ');
disp('Because the initial position of the three carts is not specified,');
prompt = 'please provide which two carts will collide first in the form ''[CartA CartB]'': ';
col_0 = input(prompt);
versus how it looks now:
prompt = ['\nBecause the initial position of the three carts is not specified, please',...
'\nprovide which two carts will collide first in the form ''[CartA CartB]'': '];
col_0 = input(prompt);
In short, you can concatenate portions of the entire prompt by declaring it as a string array and inserting \n where you see fit.
I know that there are hash functions that from a variable length input can give a fixed output. To take the simplest one, using the module of ten no matter how big is the input number I will always get an output between 0 and 9.
I need to do have from an unknown password, a variable length output. My first thought was to use the module, increasing the prim number as much as many digits I need to have as output.
My problems are:
I must handle short passwords as well as I would with long passwords;
I don't know how long should the output be before writing the program, and even though I would know after the user has set the password I may need to change it if he modifies the file.
My first thought was using a simple function and modify it based on my needs.
If I have to hash 123 but I need to have 5 characters as output, that's what I would do:
I add 2 zeros on the right, changing the input to 12300;
I take the lowest 5 digits prime number (10007);
And I then I have my hash doing 12300 % 10007 = 02293.
But since I would probably need output in the order of hundreds if not thousands I'm pretty sure module is not the solution to my problem.
I could also try to create my own hash function, but I have no idea how to verify if it works or if it's trash.
Are there some common solutions in literature for this kind of problem?
Im having some trouble with using text as an condition for a while loop, currently the basic coding is:
result=struct('val','yes');
while result.val=='yes'
result.val=input('more digits?');
end
So as you see, what Im trying to do is keeping the loop going as long as the user types in 'yes'. But thats one of the probelmes I am having; Is there a way to get rid of the need to write the ''(e.g yes instead of 'yes')? Secondly, when I run the code it gives me the error message "Error using == ,Matrix dimensions must agree.". I realise this have to do with the word yes being longer than no, but I don't know how to fix it. It's not really an issue though considering its the the program ends anyway, but it is an annoyance I would like to get rid off.
To compare strings, use strcmp, or strcmpi to ignore case. It will handle comparison of different length strings. For example:
strcmpi(result.val,'yes')
If you want to search for a substring, such as just a 'y', at the beginning of the input, consider strncmpi (strncmpi(result.val,'y',1)) or just check the first character (result.val(1)).
When working with unpack, I had hoped that b3 would return a bitstring, 3 bits in length.
The code that I had hoped to be writing (for parsing a websocket data packet) was:
my($FIN,$RSV1, $RSV2, $RSV3, $opcode, $MASK, $payload_length) = unpack('b1b1b1b1b4b1b7',substr($read_buffer,0,2));
I noticed that this doesn't do what I had hoped.
If I used b16 instead of the template above, I get the entire 2 bytes loaded into first variable as "1000000101100001".
That's great, and I have no problem with that.
I can use what I've got so far, by doing a bunch of substrings, but is there a better way of doing this? I was hoping there would be a way to process that bit string with a template similar to the one I attempted to make. Some sort of function where I can pass the specification for the packet on the right hand side, and a list of variables on the left?
Edit: I don't want to do this with a regex, since it will be in a very tight loop that will occur a lot.
Edit2: Ideally it would be nice to be able to specify what the bit string should be evaluated as (Boolean, integer, etc).
If I have understood correctly, your goal is to split the 2-bytes input to 7 new variables.
For this purpose you can use bitwise operations. This is an example of how to get your $opcode value:
my $b4 = $read_buffer & 0x0f00; # your mask to filter 9-12 bits
$opcode = $b4 >> 8; # rshift your bits
You can do the same manipulations (maybe in a single statement, if you want) for all your variables and it should execute at a resonable good speed.