CODEWITHSUNDEEP
c++
Grant H Peterson
Grant H Peterson

Reputation: 31

C++ can a user use cin to create a new string?

I made a dictionary. My goal is to have the user enter new words and define them.

I think I have the 'define words' part down, and I have the rest down. I wrote an example of kinda what I am looking for below. I don't want someone to do it for me; I just want to know if there is a way to do this and where I could learn more.

Right now, I am using C++ for Dummies and Sam's Teach Yourself For Teachers.

string newword
string word

cout << "Please enter a word" >> endl;
cin >> word;
if (word == newword)
{
    create string <newword>; // Which would make the following
                             // source code appear without
                             // actually typing anything new
                             // into the source code.
}  
string newword
string word
string word2 // which would make this happen

cout << "Please enter a word" >> endl;
cin >> word;
if (word == newword)
{
    create string <newword> 
}

Upvotes: 3

Views: 311

Answers (2)

Aesthete
Aesthete

Reputation: 18850

I would use std::map since, well, it's a dictionary style container. The map container is perfect for this situation, and you can provide unique keys to match with other data. Since a typical dictionary only has one entry for each word, this is perfect.

A typedef allow us to define a type with a name. It is helpful here here as we don't have to type std::map<std::string, std::string> over and over. Imagine each time you see Dictionary, it is replace with std::map<std::string, std::string>

// Map template requires 2 types, Key type and Value type.
// In our case, they are both strings.
typedef std::map<std::string, std::string> Dictionary;
Dictionary myDict;

Then I would ask the user for entries, and then ask them to define their entries.

std::string word;
std::cout << "What word would you like added to the dictionary?" << std::endl;
std::cin >> word;

std::string definition;
std::cout << "Please define the word " << word << std::endl;
std::cin >> definitiion;

Next step would simply insert the word and it's definition into the dictionary. Using the [] operator on a map, we replace any entry that already exists for the supplied key word. If it doesn't exist already, it will be inserted as a new entry. Note that any previously defined word of the same name will now have a new definition!

myDict[word] = definition;

Running this would produce something similar to:

>> What word would you like added to the dictionary?
>> Map
>> Please define the word Map
>> Helps you find things

Accessing definitions in the map is now trivial:

myDict["Map"]; // Retrieves the string "Helps you find things"

Upvotes: 3

j_random_hacker
j_random_hacker

Reputation: 51226

EDIT: My answer only shows you how to build a list of words without definitions. Hopefully it will open some mental doors, but to accomplish your main goal of attaching a definition to each word, you'll want to use a map instead of a vector, as Aesthete's answer shows.

What you need is a variable containing a collection of strings. One of the easiest to use, and most commonly used, is a vector:

// At the top of your program
#include <vector>

...

vector<string> words;

...

cout << "Please enter a word" << endl;
cin >> word;
words.push_back(word);     // This adds word to the end of the vector.

A vector behaves very much like an array in that if you have a vector called words, you can access the (i+1)th element using the syntax words[i]:

cout << "The 3rd word is " << words[2] << endl;

You can replace the 2 above with some other more complicated expression, including one that depends on variables. That allows you to do things like list all the words.

for (int i = 0; i < words.size(); ++i) {
    cout << "Word " << (i + 1) << " is " << words[i] << endl;
}

etc.

Upvotes: 1

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