C++ Cin input to array

Question

I am a beginner in c++ and I want to enter a string as character by character into an array , so that I can implement a reverse function .. However unlike C when the enter is hit a '\n' is not insterted in the stream.. how can I stop data from being entered ?

my code is :

#include<iostream>
#include<array>
#define SIZE 100
using namespace std;

char *reverse(char *s)
{
    array<char, SIZE>b;
    int c=0;
    for(int i =(SIZE-1);i>=0;i--){
        b[i] = s[c];
        c++;
    }

    return s;
} 

int main()
{
    cout<<"Please insert a string"<<endl;
    char a[SIZE];
    int i=0;
    do{
        cin>>a[i];
        i++;
    }while(a[i-1]!= '\0');

    reverse(a);

    return 0;
}

Answer 1

When you read character by character, it really reads characters, and newline is considered a white-space character.

Also the array will never be terminated as a C-style string, that's not how reading characters work. That means your loop condition is wrong.

To begin with I suggest you start using std::string for your strings. You can still read character by character. To continue you need to actually check what characters you read, and end reading once you read a newline.

Lastly, your reverse function does not work. First of all the loop itself is wrong, secondly you return the pointer to the original string, not the "reversed" array.

---

To help you with the reading it could be done something like

std::string str;
while (true)
{
    char ch;
    std::cin >> ch;
    if (ch == '\n')
    {
        break;  // End loop
    }

    str += ch;  // Append character to string
}

Do note that not much of this is really needed as shown in the answer by Stack Danny. Even my code above could be simplified while still reading one character at a time.

Answer 2

Since you tagged your question as C++ (and not C) why not actually solve it with the modern C++ headers (that do exactly what you want, are tested, save and work really fast (rather than own functions))?

#include <string>
#include <algorithm>
#include <iostream>

int main(){
    std::string str;
    std::cout << "Enter a string: ";
    std::getline(std::cin, str);

    std::reverse(str.begin(), str.end());

    std::cout << str << std::endl;

    return 0;
}

output:

Enter a string: Hello Test 4321
1234 tseT olleH