Read the next line of text

I just need a quick answer.

I have a simple program that reads names from a txt file, but I don't know how to get to read the next name.

Code:

---

#include <iostream>
#include <fstream>
#include <string>

using namespace std;
   
float average;

int main()
{
    ifstream infiledudes;
    string name;
    infiledudes.open( "people.txt" );
   
    infiledudes>>name;
   
    cout<<"your name is"<<name;
}

---

Use a loop.

sorry could you show me an example?

Code:

---

    while ( infiledudes>>name ) {
        cout<<"your name is"<<name;
    }

---

To read 5 names you could do this:

Code:

---

infiledudes>>name;
cout<<"your name is"<<name;

infiledudes>>name;
cout<<"your name is"<<name;

infiledudes>>name;
cout<<"your name is"<<name;

infiledudes>>name;
cout<<"your name is"<<name;

infiledudes>>name;
cout<<"your name is"<<name;

---

Now, what if you wanted to read 10,000 names? Are you willing to write those lines 10,000 times? Whenever you find yourself repeatedly writing the same lines of code, you can employ a loop:

Code:

---

while(infiledudes>>name)
{
      cout<<"your name is"<<name;
}

---

That while loop will read all the names in the file or until there is some kind of error reading from the file. The statement:

infiledudes>>name

will evaluate to false if there is any kind of error reading from the file.

If you only want to read the first 10 names from your file, you could do this:

Code:

---

for(int count = 1; infiledudes>>name; count <= 10)
{
      cout<<"your name is"<<name;
}

---

Thanks. It works but I can't fully understand why it works. Why doesn't it just keep reading the same line over and over?

Also, say i wanted to skip the first line of text, and go straight to the 3rd one for example, how would i do that?

Read in the first two lines, but don't cout<< them.

Quote:

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Originally Posted by dra

Why doesn't it just keep reading the same line over and over?

---

the short answer: ifstream reads the requested number of bytes from the file and then autmotically moves forward.

oh. I see. thanks

i'm not in a very helpful mood tonight, but perhaps running this might help you understand..

Code:

---

//#include <iostream.h> EDIT: dunno what the hell i was thinking
#include <iostream>
using namespace std;

int main()
{
 
    char c;
 
    cout << "Type in a word.\n"
    cout << "It will grab one char at a time\n"
   
    cin >> c;
    cout << c << endl;
 
    //don't ever use this (it's just quick and easy for example
    system("PAUSE");
 
   
    while(cin >> c)
              cout << c << endl;
 
    system("PAUSE");
    return 0;
}

---

try changing "char c" to "int c" and then input something like "100 250 457 59 1 " and see what happens.....now put a character into your input string "100 200 x 53"

i get it.

when you change char c to int c then enter then a sequence of numbers, only one is read at a time, because that's what "cin >> c" is requesting.

and when you add a character in the number sequence, because it's not an integer, it's not taken.

am I right?

more specifically, in the integer example, when it tries to read the character, cin returned false because it did not read valid data for an integer. that does not mean that it's not still in the input buffer. you could put a cin >> characterVariable after the loop and it will read the character.

alright. thanks for help. i appreciate it.

Quote:

---

Originally Posted by dra

Thanks. It works but I can't fully understand why it works. Why doesn't it just keep reading the same line over and over?

---

When you do this:

infiledudes.open( "people.txt" );

You create a thinga-ma-bob called infilesdudes that among other things understands what ">>" means, so you can do this:

infilesdudes>>name;

Your infilesdudes thinga-ma-bob also has a file pointer that moves along the file everytime you read from it, keeping track of where you are in the file. cin is also one of those thinga-ma-bobs and it understands what >> means as well, and cin also has a pointer that moves along the input every time you read from the input.

Quote:

---

Originally Posted by 7stud

If you only want to read the first 10 names from your file, you could do this:

Code:

---

for(int count = 1; infiledudes>>name; count <= 10)
{
      cout<<"your name is"<<name;
}

---

---

Time for you to sit in the corner for a 5 minute timeout. :p