Problem compiling a program, my first vector.

george89 · #1 26-Jun-2006, 02:12

I'm having a problem compiling a program that uses a vector. This is just to learn upon, but my problem stems from my book that I am reading: C++ Programming Language 3rd Edition by Bjarne Stroustrup. Seems as though, he doesn't tell you what preprocessor files are needed for vector... so I went hunting online and I believe I found out that it was <vector>. Now my problem is that it seems as though my compiler does not understand what I'm trying to express with my vector. I'm just about positive that it is the correct syntax, though, it doesn't seem to recognize it still... here is the code, it's not big at all, and following it is my compiler errors.

CPP / C++ / C Code:

#include <iostream>
#include <vector>
#include <time.h>

struct Entry
{
	int number;
};

int Index = 10;

vector<Entry> phone_book(Index);

void ReadEntry(int i)
{
	std::cout << phone_book[i] << std::endl;
}

void ResizeEntry()
{
	phone_book.resize(phone_book.size()+1);
	++Index;
}

void InputEntry(int i, int j)
{
	if ( i > index )
	{
		ResizeEntry();
	}
	phone_book[i] = j;
}

int main()
{
	srand(time(NULL));
	
	for ( int i = 0; i < 20; i++ )
	{
		InputEntry(i,rand()%1+25);
	}
	
	for ( int i = 0; i < Index; i++ )
	{
		ReadEntry(i);
	}
	
	return 0;
}

... and the gcc/g++ output...

Code:

george@geobox1 ~/cfiles/GeorgeTris/061706/trashtheseorlearn $ g++ -g Vector.cpp -Wall -Wextra -o Vector
Vector.cpp:12: error: expected constructor, destructor, or type conversion before '<' token
Vector.cpp: In function `void ReadEntry(int)':
Vector.cpp:16: error: `phone_book' was not declared in this scope
Vector.cpp:16: warning: unused variable 'phone_book'
Vector.cpp: In function `void ResizeEntry()':
Vector.cpp:21: error: `phone_book' was not declared in this scope
Vector.cpp: In function `void InputEntry(int, int)':
Vector.cpp:27: error: ISO C++ forbids comparison between pointer and integer
Vector.cpp:31: error: `phone_book' was not declared in this scope
Vector.cpp:31: warning: unused variable 'phone_book'
george@geobox1 ~/cfiles/GeorgeTris/061706/trashtheseorlearn $

I'm I doing something incorrect?

MichaelS-R · #2 26-Jun-2006, 03:01

I think that you have missed the point with vectors... There are lots of errors in your code and I am not clear what you are really trying to achieve. Your best bet would be to start with something really simple:

Create a vector of int.
Add the values 10, 20, 30, 40 to the vector (forget about random numbers etc. - make sure you get out what you put in in the order you expect)
Print all the values out from the beginning to the end.

Later on put a class into the vector.

Blake · #3 26-Jun-2006, 21:10

there's no need to make a struct for an entry. Just use a typedef. That will make your life easier, and it will simplify debugging.

CPP / C++ / C Code:

typedef int Entry;

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Problem compiling a program, my first vector.

Re: Problem compiling a program, my first vector.

Re: Problem compiling a program, my first vector.