wrong answer from boolean function [closed] - c++

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Closed 10 years ago.
My boolean function check_gift is not working properly.
I copied a txt file into the vector giftstore. Now I want to check if a given item is in the store. To test the function check_gift I took an item from the actual txt file but the function gives the wrong answer. It returns false instead of true.
What am I doing wrong?
#include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include <cstdlib>
#include <string>
#include <cassert>
using namespace std;
typedef vector<string> Wishes;
int size(Wishes& w){ return static_cast<int>(w.size()); }
struct Wishlist
{
double budget;
Wishes wishes;
};
struct Gift
{
double price;
string name;
};
typedef vector<Gift> Giftstore;
int size(Giftstore& g) { return static_cast<int>(g.size()); }
void read_wishlist_into_struct(ifstream& infile, Wishlist& wishlist)
{
double b;
infile>>b;
wishlist.budget=b;
int i=0;
string name;
getline(infile,name);
while(infile)
{
wishlist.wishes.push_back(name);
i++;
getline(infile,name);
}
infile.close();
}
void show_wishlist(Wishlist wishlist)
{
cout<<"Budget: "<<wishlist.budget<<endl<<endl;
cout<<"Wishes: "<<endl;
for(int i=0; i<size(wishlist.wishes); i++)
{
cout<<wishlist.wishes[i]<<endl;
}
cout<<endl;
}
void read_giftstore_into_vector(ifstream& infile, Gift& gift, Giftstore& giftstore)
{
double p;
string name;
int i=0;
infile>>p;
while(infile)
{
gift.price=p;
getline(infile,name);
gift.name=name;
giftstore.push_back(gift);
i++;
infile>>p;
}
infile.close();
}
void show_giftstore(Giftstore giftstore)
{
cout<<"All possible gifts in giftstore: "<<endl<<endl;
for(int i=0; i<giftstore.size(); i++)
{
cout<<giftstore[i].price<<"\t"<<giftstore[i].name<<endl;
}
cout<<endl;
}
bool check_gift(Giftstore giftstore, string giftname)
{
int i=0;
while(i<size(giftstore))
{
if(giftstore[i].name==giftname)
{
cout<<"Yes"<<endl;
return true;
}
else
{
i++;
}
}
return false;
}
void clear(Wishlist& b)
{
b.budget=0;
while(!b.wishes.empty())
{
b.wishes.pop_back();
}
}
void copy(Wishlist a, Wishlist& b)
{
b.budget=a.budget;
for (int i=0; i<size(b.wishes); i++)
{
b.wishes.push_back(a.wishes[i]);
}
}
int main ()
{
ifstream infile2("giftstore.txt");
Gift gift;
Giftstore giftstore;
read_giftstore_into_vector(infile2, gift, giftstore);
show_giftstore(giftstore);
string giftname;
giftname="dvd Up van Pixar";
bool x;
x=check_gift(giftstore, giftname);
cout<<"in store?: "<<x<<endl;
return 0;
}

Answer 1

Learn how to debug. If you cannot trace line-by-line through your code, then try to keep some kind of log.
For now at least output this to the console.
In your case
1. Verify the input file opened successfully
2. Print out each gift as you read it in.
would be a good way to start.
If you want to be able to put multiple log statements in and then remove them later, you can use a macro which can be turned off in one place.
Logging is a fairly tricky skill to be effective for large projects which continue to run into production, however you should learn how to do it in the short-term to debug your program.
We here cannot even see what is in your input file. This is why people are downvoting your question.
Ok: Now you've told me your issue is you need to trim whitespace from the front of each string you read in.
There are multiple ways to do that but
trimmed = s.substr( s.find_first_not_of(" \n\r\t" ) );
will probably work for now.
However my original answer still holds: please learn to debug. If you'd outputted the strings as you read them in, you would have seen these leading spaces.