String subscript out of Range

Question

0.00/5 (No votes)

See more:

Hey,

I want to know how can i rid of "string subscript out of range" error?
Or how to initialize the string to get rid of this error?

C#

bool Find_Student(Administrator &student)
{
    string sline,stemp;
    int counter=1;
    bool isFound=false;
    int iStudent_num=0;
    stemp=student.return_roll();   //gets roll number from class, works fine
    int sSize=stemp.length();
    ifstream myfile("student.txt");
    while(!myfile.eof())
    {
        counter=1;
        getline(myfile,sline);
        iStudent_num++;
        while(stemp[counter]==sline[counter])    //give error here while debugging
        {
            counter++;
            if(counter==7)
            {
                isFound=true;
                break;
            }
        }
   //////Leave the rest of stuff/////
        if(isFound==true)
        {
                student=fetch_data(sline);
                break;
        }
    }

    myfile.close();
    return isFound;
}

/////////student.txt///////

l114443$Talha Jamil$samsung$12$17$2004$UnderGraduate$!
l114445$Kamran Javed$jannat123$12$12$2009$UnderGraduate$!
l114093$Imran Khan$pluto123$11$4$2009$UnderGraduate$!
l114444$Jamil Ahmed$origin123$11$12$2009$UnderGraduate$!
l114606$Zain Malik$samsung$9$16$2009$Graduate$!
l114441$Saad Kamran$samsung$11$4$2004$Graduate$!

Suppose Input given in Roll_num is l114441

Posted 7-Dec-12 3:31am

saad_lah

Updated 7-Dec-12 4:31am

v2

Add a Solution

Comments

André Kraak 7-Dec-12 9:38am

Please share any relevant code with us, seeing the code might us help understand the problem you are facing.

If you wish to change your question use the Improve Question button.

saad_lah 7-Dec-12 10:33am

srry for that, but actual code is too much inter-related with other classes and func. and it is not possible for me to post the complete project...this is another code with same error

lewax00 7-Dec-12 10:06am

Stop trying to access indexes >= length of the string. Without seeing the code that's all I can figure out.

3 solutions

Solution 2

If your input is "l114441" I can see a problem right away - you keep going until counter is 7, but the length of the string is 7, and because it is 0 based the highest index is 6. On your final iteration, you try to access index 7, which would be the 8th character, but there isn't an 8th character.

For this code, you'd want to stop when counter is 6, not 7. I imagine your other code has a similar problem.

Posted 7-Dec-12 4:42am

lewax00

Comments

saad_lah 7-Dec-12 10:52am

No, counter starts from 1 to 7, i am neglecting first character 'l' (common in all)
so sline[7] is correct, in case of sline[6] it will stop at l114443 and will not check the others because l11444 == l11444 satisfies

lewax00 7-Dec-12 10:59am

Never mind, you're right, because it increments it before checking it, and never uses 7 as an index.

Solution 3

Why not use the std::string::compare[^] for this?

C++

if( !sline.empty() && sline.lenght() >= sSize && sline.compare( 0, sSize, stemp ) )
{
    student=fetch_data(sline);
    break;
}

Posted 7-Dec-12 4:45am

André Kraak

Comments

saad_lah 7-Dec-12 10:59am

No, it doesnot enters in 'if' condition and gives error "Not found"
although i have corrected it by my way

while(!myfile.eof())
{
counter=1;
getline(myfile,sline);
iStudent_num++;
size=sline.length();
if(size>0)
{
while(stemp[counter]==sline[counter])
{
counter++;
if(counter==7)
{
isFound=true;
break;
}
}
}
if(isFound==true)
{
student=fetch_data(sline);
break;
}
}

just by adding line if(size>0)

saad_lah 7-Dec-12 11:02am

well thanks, i learned some new functions with strings just like sline.empty() or sline.compare( 0, sSize, stemp ) by your answer :)

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Accepted Answer · 2012-12-07T04:35:00

The problem is that if the data returned by your getline function is less than the length of stemp, you will get an error. For example, if the line it reads is empty, you will immediately get a problem.

C++

counter=1;
getline(myfile,sline);
iStudent_num++;
while(stemp[counter]==sline[counter])    //give error here while debugging

Try it: put a breakpoint on the getline, and see what it returns each time. Then add a check to ensure there are at least as many characters as you are going to compare against before you enter the loop!

String subscript out of Range

3 solutions

Solution 1

Solution 2

Solution 3

Add your solution here

Preview 0

Existing Members

...or Join us