Limit number entered and repeating question

[firedragon1]

Hi guys, i need some help. (part 1) , i wanted to do a part where if you enter a number bigger than 1000 or smaller den 0 than it will show a output of Invalid input . Try again, Then it will prompt you to key in a new value again. however the code i used does not ask me the question again but just stop there, may i ask why too?
( part 2) , the code shown is the last part of my program, i wanted to make a code whereby after it show the material recommended , it will ask me if i wish to continue arnot, if i do , then it will display the code i show in part1

thanks alot for helping !

//part1
  cout <<"Please enter the ultimate tensile strength (UTS) of material needed ( highest 1000 ): " ;
	cin >>strength;

	while(!(cin >> strength) || strength < 0 || strength > 1000) //this is the part

	{
		
		cout << "Invalid input.  Try again: ";
	}

//part 2
cout <<"The material that we recommend you to use is"<<material<<"."<<endl<<"Thanks for choosing xxx calculator"<<endl ;

[naaissus]

You have two successive cin statements, line 4 and line 6, so program is waiting for another input. Try entering 5 and then 1005 and see what will gonna happen.

This will work:

while(strength < 0 || strength > 1000) //this is the part
{
    cout << "Invalid input.  Try again: ";
    cin >> strength;
}

Or just remove first cin statement (line 4).

EDIT (part 2)

do {
    // ...code...
    cout <<"The material that we recommend you to use is"<<material
    <<"."<<endl<<"Thanks for choosing xxx calculator"<<endl;
    cout << "Continue y/n: ";
    char ans;
    cin >> ans;
    if (ans == 'N' || ans == 'n') break;
} while(true);

[firedragon1]

hi thanks for help ! :D

i understood the first part and i added in the cin>> strength

but for the part2 i still dont understand

----------------------------------------------------------------------------------------------------

cout << "Continue y/n: ";
char ans;
cin >> ans;
if (ans == 'N' || ans == 'n')
{
break;

}
while(true);

---------------------------------------------------------------------------------------------------

there was a red line for the break; part stating break statement can only be used in loop or switch

also , for the last part if the break manage to work , what should i use if i want it to repeat back to the first code i use? like some kind of loop whenever i say yes i wish to continue

my whole code now is

-----------------------------------------------------------------------------------------------------


#include <iostream>
#include <string>
#include <cmath>

using namespace std;

int main()
{
double strength;
string material ;
string A = "Plastic" ;
string B = "Wood" ;
string C = "Metal" ;
string response ;

string userID, password; // For login
const string stdUserID="test123";
const string stdPassword="test1234";
int i=0;

cout<<"Welcome to xxx Calculator"<<endl;

cout <<"----------Login Screen------------\n"; //For login

while ( i < 3 )

{

cout <<"Please enter your userID:\t";
cin>>userID;

cout <<"Please enter your password:\t";
cin>>password;

if (userID.compare (stdUserID) ==0 && password.compare (stdPassword) ==0 )
{

cout <<"Login successful ! \n";
break; // exit loop after display welcome message

}

else

{

cout <<"You have entered an invalid user ID or password , please try again \n" ;
i++;

}

}

if (i==3)

cout <<"\nYou have reached maximum number of trials. Access Denied! \n" ;




cout <<"Please enter the ultimate tensile strength (UTS) of material needed ( highest 1000 ): " ;
cin >>strength;

while(strength < 0 || strength > 1000) //this is the part
{
cout << "Invalid input. Please enter a value between 0 and 1000 : ";
cin >> strength;
}

if ( strength < 10 )

material = A ;

else if ( strength < 20 )


material = B ;

else

material = C;




system("Color 5A");
std:: cout <<"The material that we recommend you to use is"<<material<<"."<<endl<<"Thanks for choosing xxx calculator"<<endl ;


cout << "Continue y/n: ";


cout << "Continue y/n: ";
char ans;
cin >> ans;
if (ans == 'N' || ans == 'n')
{
break;

}
while(true);


system ("pause");
return 0;

}

-------------------------------------------------------------------------------------------------

so i wanted it to go back to the enter the strength of the material part,

thanks alot ! and allow after the 1st round of repeating still allow the DO you wish to continue part appear

[naaissus]

Pls use code tags and indent code properly :D

You forgot to write do { before cout <<"Please enter... and to put } next to while(true). What we are trying to do here is to create an infinite loop to execute that part of program for infinity but also we want to break that loop if user enters 'N' or 'n'.

Btw you typed cout << "Continue y/n: "; twice.

You might want to exit the program or something like that if access is denied, not to just continue normal execution of it. Returning from main exits the program, so you can use return 0; to accomplish that.

[TwilightSpectre]

First, please use code tags and format your code, so that it's actually readable.

I don't know exactly what's wrong, but from appearances it seems you're trying to do a do while loop... where you seem to have forgotten to add a do. For example:

#include <iostream>
// ...

int main() {
    do {
        // ...
        std::cout << "Continue [YN]? ";
        char ans;
        std::cin >> ans;
        if (ans != 'Y' && ans != 'y')
            break;
    } while (true);

    return 0;
}