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stuck with strings and there relation to a file.

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Join Date: Jul 2008

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amrith92

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Re: stuck with strings and there relation to a file.

#11

May 25th, 2009

Much better (compared to the other revisions)! But you still haven't fixed //< MARKER (2) from my previous post! cin will not simply accept an array of characters. You have got to use the getline statement for this as well. Replace that with the following instead:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
cin.getline(strSearchData, 255, '\n');
cin.getline(strSearchData, 255, '\n');

// Behold the above [code=cplusplus] tags... its not very hard to use, see ArkM's post above

Also, you store the result of your string compare in a char . strcmp returns an int , so store it one. Otherwise, forget bothering to waste a whole variable to do this, and directly set it as the condition in your if-else construct, so that you'll get something like: if(strcmp(string1, string2) == 0){ ... }

> still trying to work out how or where in my code i could use bubble sort to search for a particular name in a file

Bubble sort isn't a searching algorithm. As the name implies(strongly), it is an algorithm for sorting an array's contents. If it is a searching technique that you are looking for, then try the Binary-Search algorithm. For more information on the binary-search algorithm, see this.

A sample algorithm you could follow to search for a name using B-Search:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
1. Load all first names into an array of strings.
2. Apply B-Search algorithm to search for a given name
1. Load all first names into an array of strings.
2. Apply B-Search algorithm to search for a given name

> how to call a function that uses void

Which function? And what do you mean, "uses void"?

Last edited by amrith92; May 25th, 2009 at 3:40 pm.

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brightsolar brightsolar is offline

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Re: stuck with strings and there relation to a file.

#12

May 25th, 2009

just a genearal function that has void infront of it rather than

int. i was trying to use code tags but i used [code = c++] not [code =cplusplus] in furure i will do so thanks for the help everyone.

binary searching you say okay will look and try thanks.

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vmanes

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Re: stuck with strings and there relation to a file.

#13

May 25th, 2009

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Originally Posted by amrith92

Much better (compared to the other revisions)! But you still haven't fixed //< MARKER (2) from my previous post! cin will not simply accept an array of characters. You have got to use the getline statement for this as well. Replace that with the following instead:
Help with Code Tags

C++ Syntax (Toggle Plain Text)
cin.getline(strSearchData, 255, '\n');
cin.getline(strSearchData, 255, '\n');

cin >> can be used to enter a string (array of char) - it's perhaps the simplest input method to use. But, it is also the most dangerous, as it doesn't know when to stop storing to the array. And, it cannot get a multi-word input. getline( ) is the generally better and safer choice, but not the only chooice.

But, brightsolar still has the mistake of using an unitialized pointer as the destination of that input action - a point I made in my earlier post.

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Join Date: Jul 2008

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amrith92

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Re: stuck with strings and there relation to a file.

#14

May 25th, 2009

> just a general function that has void infront of it rather than int.

Follow this example:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <iostream>
 
using namespace std;
 
void MyFunc(int num)
{
    cout << num;
}
 
int AnotherFunc()
{
    cout << "AnotherFunc Called!";
    return 0;
}
 
int main()
{
    cout << "A call to MyFunc : ";
 
    MyFunc(10);                       // Prints "10" in console
    AnotherFunc();                   // Prints "AnotherFunc Called!" in console
    cout << AnotherFunc();      // Prints "AnotherFunc Called!" and "0" to Console (Return value of function, AnotherFunc)
 
    cout << MyFunc(25);           // Invalid! Will cause an error! Function doesn't return anything to output to console!
 
    int num = MyFunc(25);             // Invalid!
    int nextnum = AnotherFunc();  // Valid! nextnum now holds 0
 
    return 0;
}
#include <iostream>

using namespace std;

void MyFunc(int num)
{
    cout << num;
}

int AnotherFunc()
{
    cout << "AnotherFunc Called!";
    return 0;
}

int main()
{
    cout << "A call to MyFunc : ";

    MyFunc(10);                       // Prints "10" in console
    AnotherFunc();                   // Prints "AnotherFunc Called!" in console
    cout << AnotherFunc();      // Prints "AnotherFunc Called!" and "0" to Console (Return value of function, AnotherFunc)

    cout << MyFunc(25);           // Invalid! Will cause an error! Function doesn't return anything to output to console!

    int num = MyFunc(25);             // Invalid!
    int nextnum = AnotherFunc();  // Valid! nextnum now holds 0

    return 0;
}

Infer the results of the above code, and you'll get the answer to your question. It also illustrates how you can use functions that return void as opposed to some other data type, and how not to use them.

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Join Date: Jul 2008

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amrith92

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Re: stuck with strings and there relation to a file.

#15

May 25th, 2009

> cin >> can be used to enter a string (array of char) - it's perhaps the simplest input method to use.

Whoops! Sorry for the wrong info I provided! I guess I forgot about this fact because I've been told (repeatedly) never to use this when I was learning the basics, and consequentially forgot that we can do this...

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Join Date: May 2009

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brightsolar brightsolar is offline

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Re: stuck with strings and there relation to a file.

#16

May 28th, 2009

thanks everyone project's not complete no searching but my lecturer wanted it so did not have time to play around more with searching will try now in spare time ty.