reading txt file into vector<string>

[gaurav10]

hi
i have a file dictionary.txt which contains a list of four-letter words which i have to read into a string vector.
i have written the following code

char* char2str(char);       //convert single char to null terminated string

int main()
{
    vector<string> dict;
    ifstream in("dictionary.txt");
    char *temp, ch;
    int i=0;
    while(in)
    {
             temp = new char[5];
             while(i<4)
             {
                       in.get(ch);
                       if(ch>='a' && ch<='z')
                       {
                                
                                strcat(temp, char2str(ch));
                                 i++;
                       }
             }
             dict.push_back(temp);
             i=0;
             delete temp;
    }
    
    
    for(int k=0; k<dict.size()-1; k++)
    cout<<dict[k]<<endl;
    system("PAUSE");
    return 0;
}         

where the function chsr2str is

char* char2str(char c)
{
      char *str = new char[2];
      str[0] = c;
      str[1] = '\0';
      return str;
}

the output of this program is

trap
game
?=frog
€?=plan
beam
grim
list
bane
span
true
Press any key to continue . . . 

please tell me why do i get those characters before the 3rd and 4th words.
thank u

[sammy34]

At line 11 you are dynamically allocating memory for 5 characters. After this is executed, temp points to the first of 5 characters in memory, which have not been initialised (i.e. they contain junk values).

What I think you want to do is replace the 'junk' values at index of temp by the character that you read:

	while(in)
	{
		temp = new char[5];			 
		while(i<4)
		{
			in.get(ch);
			if(ch>='a' && ch<='z')
			{
				// Put the character at position 'i' in temp
				temp[i] = ch;
				i++;
			}
		}
		// Don't forget to add the null string-terminating character!
		temp[4] = '\0';
		dict.push_back(temp);
		i=0;             
		delete temp;
	}

That worked for me. Also, if you know in advance that you're only dealing with 5-character arrays of chars, you don't have to dynamically declare it. It's faster and more efficient in this case to just statically declare it:

char temp[5];

Also note that if your file contains 4-letter words with capital letters you will get unintended behaviour. Consider what you can do to fix this.

Hope that helps.

[Duthomhas]

What's wrong with just:

vector <string> dict;
ifstream inf( ... );
string word;
while (inf >> word)
  {
  dict.push_back( word );
  }

[gaurav10]

thanks a lots sammy34 and Duoas, both methods work perfectly fine
however in sammy34's code i have to use j<dict.size()-1 in final for loop and in Duoas' code i have to use just j<dict.size()
using j<dict.size() in first method gives an extra row of e's in output
why is this so?

[sammy34]

Because Duoas' code is better than mine :). In Duoas' code, note that the while loop will terminate when there is no more to read in the file. In my/your code, we go once more through (adding another element to dict as we go) because we read from the file INSIDE the while loop. I hope I explained that well enough...