#dash 2 Syntax error redirection unexpected

111 messages · Page 1 of 1 (latest)

placid nacelle
# 
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
    int T;
    string str;
    vector<char> ops = {'<', '[', ']'};
    cin >> T;
    for (int i = 0; i < T; i++) {
        vector<char> chars;
        int pos = 0;
        string result = "";
        getline(cin, str);
        for (int j = 0; j < str.length(); j++) {
            char cChar = str[j];
            if (chars.size() == 0 && find(ops.begin(), ops.end(), cChar) != ops.end()) {
                continue;
            } else if (cChar == '<') {
                chars.erase(chars.begin()+(pos-1));
                pos--;
            } else if (cChar == '[') {
                pos = 0;
            } else if (cChar == ']') {
                pos = chars.size();
            }
            chars.insert(chars.begin()+pos, cChar);
            pos++;
        }
    }
}

When input
1
<<hate<<<<loves[steva<en ] cs2040c< and also cs2040c

It gives the error: dash 2 Syntax error redirection unexpected

gusty isleBOT
#

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placid nacelle
#

I''m not sure why it does this, I've searched online for an answer but to no avail

deft sorrel
#

That's not a c++ error

#

It's an error code returned by your task checker

placid nacelle
#

Oh

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Wait what

#

Why does that happen

#

I'm honestly not sure which part of the code is the error

#

I've tried multiple compilers

deft sorrel
#

Cause your logic must be wrong somewhere?

placid nacelle
#

Hmm

deft sorrel
#

The error is in the logic, not a matter of compiler, how do you run your code that you get such an error?

#

(btw you are not printing anything, right?)

placid nacelle
#

Im not printing anything

deft sorrel
#

Then what is the program supposed to do?

#

Your program consumes input and does nothing, really

placid nacelle
#

So its supposed to take a string

#

Yeah im not actually done with the program yet

#

But it shouldnt have an error

deft sorrel
#

Again

#

The error is returned by whatever you check your program with

placid nacelle
#

Its supposed to take a string, read through every character, '<' means backspace, '[' means move cursor to the start of the line and ']' means move cursor to the end of the line

# 
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
    int T;
    string str;
    vector<char> ops = {'<', '[', ']'};
    cin >> T;
    for (int i = 0; i < T; i++) {
        vector<char> chars;
        int pos = 0;
        string result = "";
        getline(cin, str);
        for (int j = 0; j < str.length(); j++) {
            char cChar = str[j];
            if (chars.size() == 0 && find(ops.begin(), ops.end(), cChar) != ops.end()) {
                continue;
            } else if (cChar == '<') {
                chars.erase(chars.begin()+(pos-1));
                pos--;
            } else if (cChar == '[') {
                pos = 0;
                continue;
            } else if (cChar == ']') {
                pos = chars.size();
                continue;
            }
            chars.insert(chars.begin()+pos, cChar);
            pos++;
        }
        for (char character : chars) {
            cout << character << " ";
        }
    }   
    
}

like this

#

Still doesnt work though

#

I tried hardcoding the inputs

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And it kind of worked

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So it's something to do with the getline and the cin stuff

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But im not sure what it is

#

All I'm getting now with this code is normal program termination or

dash: 2: cannot open en]: No such file
dash: 2: my: not found
#

And I'm using multiple online compilers to test the code

deft sorrel
#

What dash?? Is that the entire code compiled?

placid nacelle
#

Yes

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This is what i got

#

Just to make it clear

#

But hardcoding the input works for some reason

deft sorrel
#

Hahahahah

#

Ok so

placid nacelle
#

Yeah

deft sorrel
#

What you are doing is something completely unrelated to c++

#

Let me explain

placid nacelle
#

Oh

deft sorrel
#

You need to pass your text to stdin (standard input) of your program

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But! Your text that you are passing is not actually passed as input! Instead it is treated as a command

placid nacelle
#

Oh

deft sorrel
#

It takes the first word

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"my"

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And tries to execute it as a command

placid nacelle
#

Wtf why tho

deft sorrel
#

It can't find a command/ program named like that

placid nacelle
#

This never happens

deft sorrel
#

It all happens after your c++ program already finished

placid nacelle
#

Ohhh

deft sorrel
#

It's a terminal/console

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That first runs your c++ program

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Then tries to interpret the thing you posted as a next command

placid nacelle
#

Oh

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But i dont get why it runs the whole program first

#

Cus I did

cin >> T
#

Oh it did ask for the number

#

Is it the getline then?

deft sorrel
#

I'm not sure you are even connected to stdin there

#

Try with some hello world, cin number cout the same number

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Anyway gotta go

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Good luck!

placid nacelle
#

Aw okay

#

Yeah it works tho

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Def connected to stdin

deft sorrel
#

Oh wait it's that problem again

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I really need to make a faq about that

placid nacelle
#

Wat problem

deft sorrel
#

Ok so, without explanation what's going on

#

Add one getline right after cin T

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Before any test cases

placid nacelle
#

Add a getline?

deft sorrel
#

Yup

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The problem is, after cin T you still have a lingering new line character there

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Add a dummy getline first to get rid of that

placid nacelle
#

Oh

deft sorrel
#

getline reads all until the end of the line

#

So after reading int

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The remaining line is empty

placid nacelle
#

Oh

deft sorrel
#

Your first line read is empty

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Ok that should be it

placid nacelle
#

Alright lemme try

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So every input

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Has like a hidden newline behind it?

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Ohhhhh it worked

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Thank u so much

deft sorrel
#

It's not hidden

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It's literally new lines

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cin>> some_int will move past spaces and new lines until it finds a number

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But leaves everything else untouched

placid nacelle
#

Oh

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Oh damn

deft sorrel
#

Imagine your input being

44 text
Hoho

In this case your getline after cin>> some int would be " text"

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Notice the space in the beginning too

placid nacelle
#

Yeah

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Wait then what even was the problem just now?

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Is it cus i cin'd a number so it ignored the newline and input?

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And then my getline in the loop only got a newline so the whole program ended and the remaining input was run as a command?

deft sorrel
#

Mhm basically yes

placid nacelle
#

Ohhhhh i understand

#

Thank u so much once again!

placid nacelle
#

!solved

gusty isleBOT
#

Thank you and let us know if you have any more questions!

#

[SOLVED] dash 2 Syntax error redirection unexpected

gusty isleBOT
#

@placid nacelle

This question thread is being automatically marked as solved.