How to randomly display an user input string using c++?

Question

I am trying to randomly display a user input string using c++ but I couldn't find a way to do. Currently I am pre defining some strings

#include<iostream>
#include<string>
#include<cstdlib>
#include<ctime>

using namespace std;

int main()
{ 
 srand(time(0));
 const string wordlist[4] = {"hi","hello","what's up","wassup"};
 string word = wordlist [rand()%4];
 cout<<word;
 return 0;
}

What I want is:- I don't want to pre define them. I want the user to type in 4 words and I will display a word from the 4 words given by the user (randomly).

`stand(time(0));` ? Some examples of using `std::cin` should right next to the examples for using `std::cout` in your favourite [c++ book](https://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list) — 463035818_is_not_an_ai, Mar 14 '19 at 19:11
`stand(time(0));` What's that function? Did you mean `srand()`? — πάντα ῥεῖ, Mar 14 '19 at 19:11
What are you actually struggling with? You seem to know how to randomly pick an index in array, is the question about getting user input? — SergeyA, Mar 14 '19 at 19:11
http://www.cplusplus.com/reference/algorithm/random_shuffle/ — Kenny Ostrom, Mar 14 '19 at 19:12
@JoyDey _"It's stand() sorry that was a typo"_ And you even repeated it :-D — πάντα ῥεῖ, Mar 14 '19 at 19:14
@JoyDey _"Yes. Im struggling with the user input."_ You probably want a `std::vector` to store user input of _words_. — πάντα ῥεῖ, Mar 14 '19 at 19:16
If the number of strings is always going to be 4, `std::array` may be a tiny increment better than `std::vector` — user4581301, Mar 14 '19 at 19:18

madhur4127 · Accepted Answer · 2019-03-14T19:32:00.720

0

To do that you will have to first remove const qualifier from wordlist array.

srand(time(0));
std::vector<string> wordlist(4);
for(auto& s: wordlist) std::cin>>s;
string word = wordlist [rand()%4];
cout<<word;

Line 3 is C++11's range based for loop, this way I can easily loop over elements of std::vector<string> without indices.
If there are multiple words in a string then use getline(cin,s) accordingly. Then input each string in a new line. But be careful when mixing cin and getline for taking input.
You can use std::array if the size is going to be fixed (i.e. 4) as mentioned in comments.

edited Mar 14 '19 at 19:32

answered Mar 14 '19 at 19:15

madhur4127

276
2
13

Doesn't look like a right approach to read the `wordlist` from user input in 1st place. – πάντα ῥεῖ Mar 14 '19 at 19:19
Got an error. Range based 'for' loops are not allowed in C++98 mode – Joy Dey Mar 14 '19 at 19:19
That is not a good approach and it is not a good answer for someone kind of new. LOL – M.K Mar 14 '19 at 19:19
1

@πάνταῥεῖ hmm... Looks like it would work (at least to a degree)? – SergeyA Mar 14 '19 at 19:20
@M.K Is there something I should clarify more? – madhur4127 Mar 14 '19 at 19:24
@madhur4127 it's working now after adding a compiler flag – Joy Dey Mar 14 '19 at 19:27
@JoyDey Prior to C++11, you can use a standard `for` loop with an index: `for(int i = 0; i < 4; ++i) std::cin >> wordlist[i];` – Remy Lebeau Mar 14 '19 at 19:34
@SergeyA, when do you think it will fail? – madhur4127 Mar 14 '19 at 19:35
@madhur4127 well, the results might be unexpected if you enter several words on the line. – SergeyA Mar 14 '19 at 19:38
@SergeyA, I think this is covered in bullet 2 of the answer. – madhur4127 Mar 14 '19 at 19:39
@madhur4127 those words were not there when I made my comment. – SergeyA Mar 14 '19 at 19:42
`for(auto& s: wordlist)` this is not definetly a loop type for a beginner @madhur4127 – M.K Mar 14 '19 at 20:16
@M.K Disagree. Range-based for is a lot harder to mess up if you are accessing the container end-to-end. – user4581301 Mar 14 '19 at 20:51
Agreed, but a lot harder to understand. @user4581301 – M.K Mar 15 '19 at 07:13

How to randomly display an user input string using c++?

1 Answers1