Trouble with while loop in for loop

[Toxiic]

This function is to verify that the user input is the same as one of the array strings, but it keeps giving the "Not valid input" since it says its not the same as the one of the strings in the array. What am I doing wrong?

void r::valid(string& target){
  for (int i = 0; i < ROWS; i++) {
		while (target != a[i][0])
		{
			cout << "Not a valid input." << endl;
			cin >> target;
		}
	}
}

[gunnerfunner]

target != a[i][0]
this matches the std::string target to the first element of a[i]. I suppose a is the array of strings? In that case you're comparing the std::string target to the first character of each of the a[i]'s.
Also your programme will print ROWS lines of output which might be superfluous if you just want a check whether or not target exists in a – an alternative way to do this might be:

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

int main()
{
   std::string a[] = {"hello", "world", "this", "is", "c++"};
   std::cout << "Enter target string \n";
   std::string target{};
   getline(std::cin, target);
   auto itr = std::find(std::begin(a), std::end(a), target);
   std::cout <<  ((itr != std::end(a)) ? "target found \n" : "not found \n");
}

[Toxiic]

Would this also work if the array is 12 rows and 3 columns, because essentially I just want to check with all the values in one column and the then check by each row.

[gunnerfunner]

is a a 2d array of strings? if so, or in general for 2d arrays, one way could be:

bool match = false;
for (size_t i = 0; i < ROWS; ++i)
{
    for (size_t j = 0; j < COLS; ++j)
    {
        if (target == a[i][j])
        {
            match = true;
            break;
        }
    }
}
if (match == true)std::cout << "Target found \n";

[Toxiic]

Yes it's a 2d array of strings

[gunnerfunner]

Yes it's a 2d array of strings

OK, see above then: http://www.cplusplus.com/forum/beginner/213581/#msg996314

in the OP you're only checking target against the first string in each row, not the others

[Toxiic]

Ok so this verifies if it's true, but I also want it to repeat in case something is false so if what the user inputs is not in the array I would have the user input it again.How would I do that?

[gunnerfunner]

you can just verify the value of match after the loops, so if match == false, not found

[Toxiic]

Ok it worked thank you. I just have one more question how do I make it work for a c-string since I am dealing with both.

[gunnerfunner]

https://www.tutorialspoint.com/c_standard_library/c_function_strcmp.htm