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fstream program help

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Join Date: Nov 2008

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jimbob90

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fstream program help

Dec 14th, 2008

program read from cin what the user wants to do ("add" a name to list) or ("lookup" a name). in add just add whatever was read in to the file. in lookup print out a line of text with the string that wa read in. hopefully that makes some sense =/

im pretty sure that the problem is in one of the loops of lookup function. (while or if else)

 Help with Code Tags 
 c++ Syntax (Toggle Plain Text) 
#include <iostream>
#include <fstream>
#include <string>
 
using namespace std;
 
void add(string);
void lookup(string);
 
int main(){
    ifstream a;
    string name, choice, name2, email, longstring;
    cin >> choice;
    if (choice == "lookup"){
              cin >> name;
             lookup(name);
    }
    else {
             cin >> name >> name2 >> email;
             longstring = name + " " + name2 + " " + email;
             add(longstring);
    }
 
    return 0;
}
void add(string longstring){
     ofstream a;
     a.open("phonedir");
     a << longstring;
     } 
void lookup (string name){
       ifstream a;
       string line;
       a.open("phonedir");
       while (!a.eof()){
             getline(cin, line);
            if (line.find(name))
               cout << line;
             else
                  "";
       }
}
#include <iostream>
#include <fstream>
#include <string>
     
using namespace std;

void add(string);
void lookup(string);
     
int main(){
    ifstream a;
    string name, choice, name2, email, longstring;
    cin >> choice;
    if (choice == "lookup"){
              cin >> name;
             lookup(name);
    }
    else {
             cin >> name >> name2 >> email;
             longstring = name + " " + name2 + " " + email;
             add(longstring);
    }

    return 0;
}
void add(string longstring){
     ofstream a;
     a.open("phonedir");
     a << longstring;
     } 
void lookup (string name){
       ifstream a;
       string line;
       a.open("phonedir");
       while (!a.eof()){
             getline(cin, line);
            if (line.find(name))
               cout << line;
             else
                  "";
       }
}

Last edited by jimbob90; Dec 14th, 2008 at 5:54 pm.

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Join Date: Feb 2008

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daviddoria daviddoria is offline

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Re: fstream program help

Dec 14th, 2008

1) make sure you open the file in append mode in the add() function (i'm not sure what the default mode is)

2)there is no need to do

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
while (!a.eof()){
getline(cin, line);
while (!a.eof()){
getline(cin, line);

you can simply do

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
while(getline(cin,line))
while(getline(cin,line))

If you don't tell us what's wrong, we can tell you how to fix it! (unless we compile it ourselves - which you're supposed to do for us! haha)

Dave

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jimbob90

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Re: fstream program help

Dec 14th, 2008

not realy sure what you meanwith add().
file:
smith joe jsmith@gmail.com
harper stephen sharper@pm.gov.ca
rococco rocky rocky@.fsign.com
output:
lookup rockylookup fred

if i find the string i need i print out the whole line that is in the file

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Join Date: Jun 2008

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mrboolf

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Re: fstream program help

Dec 14th, 2008

getline(cin, line); Shouldn't you take your line from the ifstream?

What daviddoria meant with the add function is that you are every time rewriting the file instead of just adding lines.

Also you are not closing anything.

Edit: You declare ifstream a; in main but you make no use of it.

Last edited by mrboolf; Dec 14th, 2008 at 6:18 pm.

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jimbob90

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Re: fstream program help

Dec 14th, 2008

 Help with Code Tags 
 c++ Syntax (Toggle Plain Text) 
#include <iostream>
#include <fstream>
#include <string>
 
using namespace std;
 
void add(string);
void lookup(string);
 
int main() {
    string name, choice, name2, email, longstring;
    cin >> choice;
    if (choice == "lookup"){
              cin >> name;
             lookup(name);
    }
    else {
             cin >> name >> name2 >> email;
             longstring = name + " " + name2 + " " + email;
             add(longstring);
    }
 
    return 0;
}
void add(string longstring){
     ofstream a;
     a.open("phonedir");
     add(longstring);
     a.close("phonedir");
} 
 
void lookup (string name){
       ifstream a;
       string line;
       a.open("phonedir");
       while (getline(cin, line)){
            if (line.find(name))
               cout << line;
             else
                  "";
       }
       a.close("phonedir");
}
#include <iostream>
#include <fstream>
#include <string>
     
using namespace std;

void add(string);
void lookup(string);
     
int main() {
    string name, choice, name2, email, longstring;
    cin >> choice;
    if (choice == "lookup"){
              cin >> name;
             lookup(name);
    }
    else {
             cin >> name >> name2 >> email;
             longstring = name + " " + name2 + " " + email;
             add(longstring);
    }

    return 0;
}
void add(string longstring){
     ofstream a;
     a.open("phonedir");
     add(longstring);
     a.close("phonedir");
} 

void lookup (string name){
       ifstream a;
       string line;
       a.open("phonedir");
       while (getline(cin, line)){
            if (line.find(name))
               cout << line;
             else
                  "";
       }
       a.close("phonedir");
}

when i close i get this weird error

29 no matching function for call to `std::basic_ofstream<char, std::char_traits<char> >::close(const char[9])'

note C:\Dev-Cpp\include\c++\3.4.2\fstream:708 candidates are: void std::basic_ofstream<_CharT, _Traits>::close() [with _CharT = char, _Traits = std::char_traits<char>]

got both of those two times (2 close() functions)

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jimbob90

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Re: fstream program help

Dec 14th, 2008

figured out my close doesnt work yay?
and still my lookup function doesnt work heres the input/output again
in the file

smith joe jsmith@gmail.com
harper stephen sharper@pm.gov.ca
rococco rocky rocky@.fsign.com

output

lookup rockylookup fred (printed out what I typed in, lovely)

Last edited by jimbob90; Dec 14th, 2008 at 6:39 pm.

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Join Date: Jun 2008

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mrboolf

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Re: fstream program help

Dec 14th, 2008

What prevents your program from compiling is the following:

1) close doesn't need arguments - change both a.close("phonedir"); with a.close(); .
2) else "" ; doesn't make sense. Maybe you wanted to write else cout << ""; .

Said that, your code presents at least one big problem and two minor ones.

The big one: you call add function recursively (why?) and you don't set a base case. This is bad. Delete that recursive add(longstring); line and put ther a simpler and healtier a << longstring;
The "minor" ones:

1) getline(cin, line); would likely be getline(a, line); (as you are searching a)
2) You still probably need to open your ofstream in append mode in your add function.

EDIT:

•

printed out what I typed in, lovely

that has to do with minor problem #1

Last edited by mrboolf; Dec 14th, 2008 at 6:46 pm.

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deepglue555 deepglue555 is offline

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Re: fstream program help

Jan 14th, 2009

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Originally Posted by mrboolf

getline(cin, line); Shouldn't you take your line from the ifstream?

What daviddoria meant with the add function is that you are every time rewriting the file instead of just adding lines.

Also you are not closing anything.

Edit: You declare ifstream a; in main but you make no use of it.

what is the longest string that can come from the console into 'line'

I wrote a program that is crashing because it is recieving more than 280 characters.
How can i increase the amount getline can take in or is there an alternative function which will handle greater strings from IO?????