Hi, I could use a little help if anyone would be willing.

I have some vectors which I am using to store input from a text file. Now I want to be able to store user input into a vector and output it to that file so that it replaces the old element in the file.

So for instance, if I have vector<int> vecList; as my vector and I want to replace vecList[5] with an integer entered by a user, how exactly can I do that?

Thanks

You're asking two different things:

If you want to replace a element in a vector, ,you should pop until you've reached the element you want to change (storing all the popped values somewhere in a temp-var), then push the new value in and then push all the old values back from the temp-var.

If you want to change a number in a file, read in the file and store all the values somewhere in a var. Change the value you want to change and then delete the original file, create a new one and write everything back.

The second route is the one I want to go with, but I am not sure how to do that. I really don't know how to store all the values in a variable as you say. And then I wouldn't know how to access to right value in that variable so that I could change it either.

What does your textfile look like and how many lines are in it? This is important to know to answer your question.

My text file is just 1 line of 63 elements. Some of these are string type, some are int, and some are double.

1111 Hammers 125 125 0 12.50 20.00 2222
This is the first little strip of it......the rest of the file is exactly the same just different data. This is basically the data for "Hammers", and I want to change the element immediately after Hammers which is 125. I just want to change it from the integer that it already is, to a new integer.

You could use getline() and use the space as a delimiter.
Then use an if statement to see if the word from the file matches '125' and replace it. Then write everything back.

So for instance, if I have vector<int> vecList; as my vector and I want to replace vecList[5] with an integer entered by a user, how exactly can I do that?

Simply by vecList[5] = int_from_user; To lookup a value to change, you can use std::find()

#include <algorithm>
...
vector<int> v;
...
const int value = 234;
vector<int>::iterator srch = find(v.begin(), v.end(), value);

if(srch != v.end())
{
    // increment the value by one
    *srch = value + 1;
}

How exactly do I replace it though? I understand what you are saying with using getline() and then checking to see if the word compares...but I don't understand how to replace the 125 with another number.

You shouldn't look at 125 as a number, but as just another string.

ifstream file("yourfile.txt");
if (file)
{
    std::string word;
    vector <string> array;
    while ( getline(file, word, ' '))
    {
        if (word == "something") 
               word = "something else";
        array.push_back(word);
    }
}

Now you have all your words in a vector, and you've replaced 'something' with 'something else'

It is giving me errors since "word" is a string and I am trying to manipulate an integer. But getline is a string function isn't it? So there really is no way I can use that.

Sure you can, you just have to convert your int to a string and compare it with the string that was read.

#include <sstream>

[...]

ifstream file("yourfile.txt");
if (file)
{
    std::stringstream ss;
    std::string str;
    std::string word;
    ss << 125;  // or any other number here
    ss >> str;
    vector <string> array;
    while ( getline(file, word, ' '))
    {
        if (word == str) 
               word = "something else";
        array.push_back(word);
    }
}
This question has already been answered. Start a new discussion instead.