Complies but doesn't run

Hi, I'm completely new to programming. That being said, one of the programs I made for an assignment seems to compile, but when I run it I get an error. I can't figure out why its happening. Could someone point me in the right direction?

PHP Code:

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


int main()
{
    int number;
    
    cout<<"Please enter an integer greater than or equal to 1000: ";
    string digit;
    cin>>number;
    


if (number >= 1000)

    {
        string last_three_number = digit.substr(digit.length()-3);
        string first_three_number = digit.substr(0,3);
        cout<<"Your integer with commas is " <<first_three_number + "," + last_three_number <<endl;

    }

else if (number < 1000)

    {
        cout<<"Please enter a higher integer value"<<endl;
    }

return 0;


} 


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Quote:

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Originally Posted by Rayman452

Hi, I'm completely new to programming. That being said, one of the programs I made for an assignment seems to compile, but when I run it I get an error.

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Please give us more details on the error.

Also, since you're new to programming, you need to realize that just because a program compiles, it doesn't guarantee that the program will do what you intended it to do. You still have the logical part of the whole equation to overcome. If you want a program to add two numbers, and instead you mistakingly coded to subtract them, the program may have been correct in terms of syntax, but it is incorrect in that it didn't perform the job requested.

Also, you must learn to use your debugger, as this will let you know what each variable is at each step of the program.

Regards,

Paul McKenzie

As to your error, where do you assign "digit" a value? You declare it, but you don't assign it any value. You input a value into number, and then for some reason, you assume that "digit" also has this same value as a string. C++ doesn't work that way -- variables must be assigned a known quantity for them to have something to work with.

Regards,

Paul McKenzie

But you have to give him props. Usage of stl, correct signature of main and code tags :thumb:.

Quote:

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Originally Posted by STLDude

But you have to give him props. Usage of stl, correct signature of main and code tags :thumb:.

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Yes, RayMan452 has picked a good book or teacher to learn from, unlike most newbies to C++ that post here.

Regards,

Paul McKenzie

haha i know how you feel

what you need to do is figure out a way to make digit and number equal, right now nothing is being entered,

I tried

Code:

---

   
string digit;
int number;
cin >> digit >> number;

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But that means you have to enter the number 2 times, but if you do, it works.

The best strategy for user input is to get all input as strings then parse from the string whatever you need. Parsing ints from strings is very easy with stringstreams and getting input from a user as a string makes your code robust. It is unlikely to crash even if the input comes from a dose of keyboard slapping.

I'm taking introduction to programming in my university, using Cay Horstmann's "C++ for Everyone" as my textbook. I'm also using Microsoft's visual studio 2008 as my compiler. I'm trying to write a code to insert a comma in the thousands spot.

If I enter a value less than 100, it works. If I get rid of my if statements, the code manages to work. However, with the if statement I seem to get a debug error, where "this application has requested the run time to terminate it in an unusual way. Please contact the application's support team for more information"

How do I set it up so that I only have to input the number once for it to be assigned to the string digit, and the int number? I need it to be assigned to an int number so that the if statements can check it and carry out the function.

What is parsing from the strings and how do I do it?

Code:

---

#include <iostream>
#include <string>
#include <sstream>

using namespace std;

bool StringToInt(const string &s, int &i)
{
  istringstream myStream(s);
  if (myStream>>i)
    return true;
  else
    return false;
}

int result;
int number;
string digit;

int main()
{
   
    cout<<"Please enter an integer greater than or equal to 1000: ";
    cin >> digit;

if (StringToInt(digit, result))
  {
  number = result;
  }
  else
  {
    cout << "The Number you put in is not an iterger" <<endl;
  }


if ( number >= 1000 )

    {
        string last_three_number = digit.substr(digit.length()-3);
        string first_three_number = digit.substr(0,3);
        cout << "Your integer with commas is " <<first_three_number + "," + last_three_number <<endl;

    }

else if (number < 1000)

    {
        cout << "Please enter a higher integer value" << endl;
    }

return 0;
}

---

WHEW that was strange.

Heres where i found the converter

http://faq.cprogramming.com/cgi-bin/...wer=1046996179


FYI You should comment your work more

Quote:

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Originally Posted by H aun

[CODE]

FYI You should comment your work more

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Very simple code like that doesn't need to be cluttered with comments.:mad:

:o i think its a good idea to comment a fair ammont, i comment on every line most of the time. But if you do thats ok....

Quote:

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Originally Posted by H aun

i think its a good idea to comment a fair ammont, i comment on every line most of the time.

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It is a good idea to use descriptive names for identifiers so that the code is "self-commenting". If you need to comment on almost every line, it either means that you have rather undescriptive names, or your comments are redundant.

Most of them are (haha) but thats ok. I like to know every thing on the spot with good description. Mainly i do it so that people know what the heck they are looking at when i need help, or for when i go back to backed up files so i know what it does

Quote:

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Originally Posted by H aun

:o i think its a good idea to comment a fair ammont, i comment on every line most of the time. But if you do thats ok....

---

Then either you write very non-intuitive code or you waste a lot of time. If you use self explanatory variable and function names, and keep your code nicely compartmentalized and use proper indentation and brace matching, there should be very little need to comment almost every line.

Code:

---

int a = 1; //set a to 1
if( a == 1) // see if a is equal to 1
{
...
}// end if

---

Comments like that are just plain goofy.

If you write your code properly, you'll know what it does without having to read comments.

Thanks for settin down the law man. good job, wip those programmers into shape. No useless commenting! it clogs up your code

any way i think its a good idea for a new programmer to get into the habit of commenting their code. but thats me.

So! Rayman any other problems?

Another thing you might want to do is use <cstdio> (include it), it lets you use Command Prompt comands, pause, cls, ect. used by system("commnd"), example system("pause")
i use pause A LOT!!!!

Really makes things easier

Quote:

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Originally Posted by H aun

any way i think its a good idea for a new programmer to get into the habit of commenting their code.

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It is, but one must also learn not just to comment but to comment appropriately.

Quote:

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Originally Posted by H aun

Another thing you might want to do is use cstdio (include it), it lets you use Command Prompt comands, pause, cls, ect. used by system("commnd"), example system("pause")
i use pause A LOT!!!!

Really makes things easier

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It does? It sounds like you are simulating a debugger, but back in post #2 Paul McKenzie already suggested that Rayman452 learn how to use a debugger.

no, it works in the program

Quote:

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Originally Posted by H aun

no, it works in the program

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How does it "make things easier"? I do not see how the use of such platform dependent external utilities will benefit Rayman452's program.

Incidentally, std::system() is found in <cstdlib>, not <cstdio>.

well with out the system("pauses") you need to go into command prompt, then navigate to the executibal and run it.

You put the pauses in places (well at least for me) when something is read out and nothing is being entered.

example

Code:

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void errorcm()
{
    cout << ent << " Is Not A Command" << '\n' ;
    system("pause");
    system("cls");
        help();
}

---

that paused it after displaying

Quote:

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"asdf" is not a command

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and the cleared it up, so the stuff in help() could be displayed more cleanly

also im using Dev C++ and system("") is the function for that, and the <cstdio> is not the system stuff, thanks for correcting me.

Quote:

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Originally Posted by H aun

well with out the system("pauses") you need to go into command prompt, then navigate to the executibal and run it.

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That is the way a command line program is supposed to be run (or you could run it from say, a batch file). Rayman452 is using Visual Studio 2008, and that IDE is likely to keep the console window open when running the program via the IDE. Even if it does not, inserting a break point at the end of the program should be a suitable workaround.

I dipped into Visual studios, always kicked my butt. might dip back in there