How do I validate input for the array to only accept integers?

#include <iostream>
#include <iomanip>
#include <string>
#include <string>
using namespace std;

int main()
{
    int TheNumbers[10];// An array of 10 indexes 
    int i;

    for (i=0; i<10; i  ) // accepts input 10 times
    {
        cout << "Enter a number: ";
        cin >> TheNumbers[i];
    }
    
    for (i=9; i>=0; i--) // returns inputs in reverse order
    {
        cout << TheNumbers[i] << endl;
    }
        
    // ERROR MSSG: While input is not an integer
    while(!(cin >> TheNumbers[10]))
    {
        cout << "**Inncorect input** \n" << "Please input a number: \n";
        cin.clear();
        cin.ignore(50, '\n');
    }

    return 0;
}

Enter a number: Enter a number: Enter a number: Enter a number: Enter a number: Enter a number: Enter a number: Enter a number: Enter a number: 32765
-882742640
22081
1189945728
0
0
22081
1189946384
32744
0

CodePudding user response：

You could try adding another nested loop:

static const int MAXIMUM_NUMBERS = 10;
//...
for (int i = 0; i < MAXIMUM_NUMBERS;   i)
{
    std::cout << "Enter a number: ";
    while (!(cin >> number[i]))
    {
        std::cout << "Invalid number.  Try again.\n";
        std::cout << "Enter a number: ";
        std::cin.clear(); // Clear the error.
        std::cin.ignore(10000, '\n');
    }
}

This is a simple example, there are other methods.

CodePudding user response：

The solution Thomas Mathew recommended works very well! Creating the MaxNumbers variable to use as a data type comparison, rather than trying to validate a variable to itself.

#include <iostream>
#include <iomanip>
#include <cstring>
#include <string>
using namespace std;

int main()
{
int TheNumbers[10];// An array of 10 indexes 
static const int MaxNumbers = 10;
int i;
    for (i=0; i< MaxNumbers;   i) // accepts input 10 times
    {
        cout << "Enter a number: ";
        while (!(cin >> TheNumbers[i]))
        {
            cout << "** INNCORECT INPUT*** \n" << "Enter a number: ";
            cin.clear();
            cin.ignore(50, '\n');
        }
    }
        for (i=9; i>=0; i--)
        {
            cout << TheNumbers[i] << endl;
        }
return 0;
}

CodePudding user response：

An option would be:

1. Use std::getline to read from std::cin into a std::string.
2. Use std::from_chars to check if the string contains a valid integer.

• If it does, update the count of valid integers read, and carry on.
• If it doesn't, you can optionally tell the users they gave you an invalid input.

Do this in a loop until you have read the amount of numbers you want.

Demo (reading 3 numbers only)

#include <charconv>  // from_chars
#include <iostream>  // cin, cout
#include <string>  // getline
#include <system_error>  // errc

int main() {
    int TheNumbers[3];  // An array of 3 indexes

    for (int i{}; i < 3;) {  // accepts input 3 times
        std::cout << "Enter a number: ";
        std::string number{};
        std::getline(std::cin, number);
        int n{};
        auto [ptr, ec] = std::from_chars(number.data(), number.data()   number.size(), n);
        if (ec != std::errc{} or ptr != number.data()   number.size())  {
            std::cout << "Error: invalid input\n";
        } else {
            std::cout << "OK: read " << n << "\n";
            TheNumbers[i  ] = n;
        }
    }
    std::cout << "---\n";
    for (int i{2}; i >= 0; --i) {  // returns inputs in reverse order
        std::cout << TheNumbers[i] << "\n";
    }
}

// Inputs:
//   blah
//   1
//   foo99
//   2
//   3.1415
//   4
//
// Outputs:
//   Enter a number: Error: invalid input
//   Enter a number: OK: read 1
//   Enter a number: Error: invalid input
//   Enter a number: OK: read 2
//   Enter a number: Error: invalid input
//   Enter a number: OK: read 4
//   ---
//   4
//   2
//   1