Problems debugging simple console program :: CLion

Question

I am trying to learn basic C++ after being a Java developer. So I decided to give CLion a try. I wrote this basic code just to familiarize myself with some C++ syntax.

#include <iostream>
using namespace std;

int main() {
    string word;

    cout << "Enter a word to reverse characters: " << endl;
    getline(cin, word);

    for(int i = word.length(); i != -1; i--) {
        cout << word[i];
    }

    return 0;
}

The code is functional. It reverses whatever word you input. I wanted to step through it to see variables and what not, and to test out CLion's debugger.

My problem occurs when I get to

getline(cin, word);

When I step onto this line, I enter a word and hit enter. Then step over. After I do this nothing happens; all the step over, in, etc. buttons are disabled. I am unable to continue through the loop, or run the remainder of the code.

I have used Eclipse's debugger many times for Java development without any issues. Any ideas could be helpful.

TL;DR How do I step through a C++ command line program with basic input and output using CLion?

doesn't answer your question, but you've got undefined behavior: `string word; char wordReversedArray[word.length()];` - you have an array with 0 length that you try to write into... — John3136, Oct 02 '14 at 02:07
@John3136 You're correct. I changed the code to be a little more clear. The same problem still persists. — ryndshn, Oct 02 '14 at 02:19
Could be as simple as buffering - `cout << "str";` write to the console/terminal. The console can buffer things up until it gets a newline. Try `cout << "str" << endl;` too see if that explains things... — John3136, Oct 02 '14 at 02:25
@John3136 That fixed one problem. It now prints when expected. However I'm still having the issue when inputting. — ryndshn, Oct 02 '14 at 02:39
Add a `cout` before your loop to display the word. Add a `cout` in your loop to display `i`. See if eveything is as you expect. C++ uses 0 based indexes, so `word[word.length]` isn't valid. — John3136, Oct 02 '14 at 02:46
@John3136 Yeah that's an easy work around. I was hoping to find a fix for the debugger, because I will surely be writing more advanced code that will require some sort of debugger. — ryndshn, Oct 02 '14 at 02:59
Not clear what problem you've actually got with the debugger? — John3136, Oct 02 '14 at 03:12
@John3136 The debugger options are disabled after entering a word. I am not able to step through the loop, or anything else following getline(cin, word); — ryndshn, Oct 02 '14 at 03:22
@ryan4888 Have you compiled the application with debugging support enabled? (side note, change the loop to start with `i = static_cast(word.length()) - 1`). Go to [Run | Edit Configurations dialog and change the configuration type to Debug](http://blog.jetbrains.com/clion/2014/09/clion-answers-frequently-asked-questions/) — Mohit Jain, Nov 10 '14 at 07:38

sfjac · Accepted Answer · 2015-03-07T13:44:18.040

11

I've replicated the problem - looks to me like when debugging the newline is being swallowed by the IDE and not passed back to the program. I've submitted a bug to JetBrains. I don't see a way to work around this aside from getting out of the IDE and debugging directly with GDB or another IDE.

UPDATE: This issue was fixed in the Clion EAP Build 140.1221.2. It even made the first change listed in the release notes:

The most valuable changes are:

Debugger doesn’t hang on ‘cin >>’ operator any more.

edited Mar 07 '15 at 13:44

answered Nov 14 '14 at 23:40

sfjac

7,119
5
45
69

2

Alas, this does not appear to have been fixed in the latest EAP. – sfjac Dec 10 '14 at 21:45

CodeMonkey · Answer 2 · 2014-11-12T22:41:01.843

1

Looking at your code, if everything is correct, you need to add #include <string>.

When I run this, it compiles and completes the output.

#include <iostream>
#include <string>

int main() {

    std::string word;

    std::cout << "Enter a word to reverse chars: ";
    std::getline(std::cin, word); //Hello

    for (int i = word.length() - 1; i != -1; i--) {
        //Without - 1 " olleh"
        //With    - 1 "olleh"
        std::cout << word[i];
    }
    std::cout << std::endl;
    system("pause");
    return 0;
}

edited Nov 12 '14 at 22:41

answered Nov 12 '14 at 22:28

CodeMonkey

1,136
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`std::string` on some `C++` implementations may be available with `iostream` without including `string` explicitly. Moreover if `std::string` is unavailable, you would see a compile time error and not issue while debugging. – Mohit Jain Nov 14 '14 at 05:31
1

@MohitJain true, but with `iostream`, you call `std::cin.getline(char*, streamsize)`. With `string`, you call `std::getline(std::istream, std::string)`. – CodeMonkey Nov 14 '14 at 16:05

score 1 · Answer 3 · answered Nov 14 '14 at 05:39

1

Use the following code. I have modified your code to make it workable for your purpose. :)

#include <iostream>
#include <string>
using namespace std;

int main() {
    string word;

    cout << "Enter a word to reverse characters: " << endl;
    getline(cin, word);

    for(int i = word.length() - 1; i != -1; i--) {
        cout << word[i];
    }

    printf("\n");

    system("pause");

    return 0;
}

answered Nov 14 '14 at 05:39

Naseef Chowdhury

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3
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Why are you saying it's ok to be using system("pause")? Don't you think that the beginner would benefit from some look into how to actually reverse a string in c++? `string(s.rbegin(), s.rend())` implying s is a string? – user2913685 Nov 14 '14 at 22:10
Actually don't understand what you are talking about. System("pause") actually able us to see the output window after execution of program completed. It has nothing to do with string reverse. – Naseef Chowdhury Nov 17 '14 at 08:06

Problems debugging simple console program :: CLion

3 Answers3