How to accept only certain text?

Here is my code so far. I just can't get the last 3 lines. I need to accept only text that says Total or Gas. How would I do that? I've looked up and read a lot of stuff but everything I tries doesn't work haha. any help would be great.

Code:

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


int main() {


int miles_per_year;
double gallon_gas;
double hybrid_cost;
int hybrid_mpg;
double hybrid_resale;
double cost_nonhybrid;
int non_hybrid_mpg;
double nonhybrid_resale;
int buying_crit;




    cout <<"Please answer the following questions.\n" << endl;
   
do
{
    cout <<"The estimated miles driven per year?" << endl;
    cin >> miles_per_year;
if(miles_per_year < 0)
    cout <<"Please enter a positive value." << endl;
} while(miles_per_year < 0);


do
{
    cout <<"The estimated price of a gallon of gas?" << endl;
    cin >> gallon_gas;
if(gallon_gas < 0)
    cout <<"Please enter a positive value." << endl;
} while(gallon_gas < 0);


do
{
    cout <<"The cost of a hybrid car?" << endl;
    cin >> hybrid_cost;
if(hybrid_cost < 0)
    cout <<"Please enter a positive value." << endl;
} while(hybrid_cost < 0);


do
{
    cout <<"The efficiency of the hybrid car in miles per gallon?" << endl;
    cin >> hybrid_mpg;
if(hybrid_mpg < 0)
    cout <<"Please enter a positive value." << endl;
} while(hybrid_mpg < 0);


do
{
    cout <<"The estimated resale value for a hybrid after 5 years?" << endl;
    cin >> hybrid_resale;
if(hybrid_resale < 0)
    cout <<"Please enter a positive value." << endl;
} while(hybrid_resale < 0);


do
{
    cout <<"The cost of a non-hybrid car?" << endl;
    cin >> cost_nonhybrid;
if(cost_nonhybrid < 0)
    cout <<"Please enter a positive value." << endl;
} while(cost_nonhybrid < 0);


do
{
    cout <<"The efficiency of the non-hybrid car in miles per gallon?" << endl;
    cin >> non_hybrid_mpg;
if(non_hybrid_mpg < 0)
    cout <<"Please enter a positive value." << endl;
} while(non_hybrid_mpg < 0);


do
{
    cout <<"The estimated resale value for a non-hybrid after 5 years?" << endl;
    cin >> nonhybrid_resale;
if(nonhybrid_resale < 0)
    cout <<"Please enter a positive value." << endl;
} while(nonhybrid_resale < 0);
   


    cout <<"Would you like results sorted by lowest gas consumption(\"gas\")\n or lowest total cost(\"total\")?" << endl;
    cout <<"Please enter either \"gas\" or \"total\" for how results are to be sorted." << endl;
    cin >> buying_crit;




system("pause");
return 0;


}

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I'm a 'C' person, and don't know anything about C++ other than what I've read on here - but I would think you should start by using the 'string' data type in lieu of an integer. If I'm wrong, someone here will correct me.

1) you can't store "gas" or "total" in a int variable.

2) Use std::string :) Don't forget to include <string>

Code:

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std::string test;
std::cout << "Enter 'gas' or 'total'\n";
std::getline(std::cin, test);
for ( std::string::iterator it = test.begin(); it != test.end(); ++it )
{
 (*it) = tolower((*it));
}
 
if ( test.compare("gas") == 0 )
{
 std::cout << "GAS!!!\n";
}
else if ( test.compare("total") == 0 )
{
 std::cout << "Total!!!\n";
}
else
{
 /* Did not match */
}

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The for loop changes the string to all lowercase, since the std::string.compare() function is case sensitive.

Code:

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for ( std::string::iterator it = test.begin(); it != test.end(); ++it )
{
 (*it) = tolower((*it));
}

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Or just

Code:

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std::transform(test.begin(), test.end(), test.begin(), &std::tolower);

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