Unable to exit out of do-while loop? - c++

Question

I can't figure out why the do-while loop isn't being terminated upon user entering -1 in input. Just ignore everything after the internal while loop. I know that the problem is somewhere in the while loop. I just don't see it.
int main()
{
srand(time(0));
int input;
std::string pass, company, timeS;
do
{
std::cout << "Enter password length: ";
std::cin >> input;
while(input < 8 || input > 16)
{
if(!std::cin)
{
std::cin.clear();
std::cin.ignore(100, '\n');
}
std::cout << "Password length must be between 8 and 16.\nEnter password length: ";
std::cin >> input;
}
std::cout << "Enter company name: ";
std::getline(std::cin, company);
pass = passGen(input);
time_t now = time(0);
auto time = *std::localtime(&now);
std::stringstream ss;
ss << std::put_time(&time, "%Y %b %d %H:%M:%S %a");
timeS = ss.str();
std::cout << "You passoword: " << pass << std::endl;
writeFile(pass, company, timeS);
}while(input != -1);
return 0;
}
Thanks in advance!

Answer 1

In this loop you wait for number between 8 and 16:
while(input < 8 || input > 16)
{
if(!std::cin)
{
std::cin.clear();
std::cin.ignore(100, '\n');
}
std::cout << "Password length must be between 8 and 16.\nEnter password length: ";
std::cin >> input;
}
Guess, what never comes out of that loop? Right, -1 !! =)

Answer 2

Hope this will answer your question:
int main()
{
srand(time(0));
int input;
std::string pass, company, timeS;
// do
// {
while(true){
std::cout << "Enter password length: ";
std::cin >> input;
if(input == -1){
break;
}
while(input < 8 || input > 16)
{
if(!std::cin)
{
std::cin.clear();
std::cin.ignore(100, '\n');
}
std::cout<< "=====>>>" << std::endl;
std::cout << "Password length must be between 8 and 16.\nEnter password length: ";
std::cin >> input;
}
std::cout << "Enter company name: ";
std::getline(std::cin, company);
pass = passGen(input);
time_t now = time(0);
auto time = *std::localtime(&now);
std::stringstream ss;
ss << std::put_time(&time, "%Y %b %d %H:%M:%S %a");
timeS = ss.str();
std::cout << "You passoword: " << pass << std::endl;
writeFile(pass, company, timeS);
}
// }while(input != -1);
return 0;
}
Just use
while(true){
//getting length of password
if(input == -1){
break;
}
//rest of the logic
}

Answer 3

The internal while loop will never terminate as the condition is will always be true for -1.
int main()
{
srand(time(0));
int input;
std::string pass, company, timeS;
do
{
std::cout << "Enter password length: ";
std::cin >> input;
while((input < 8 && input>=0)|| input > 16)
{
if(!std::cin)
{
std::cin.clear();
std::cin.ignore(100, '\n');
}
std::cout << "Password length must be between 8 and 16.\nEnter password length: ";
std::cin >> input;
}
if (input>0){
std::cout << "Enter company name: ";
std::getline(std::cin, company);
pass = passGen(input);
time_t now = time(0);
auto time = *std::localtime(&now);
std::stringstream ss;
ss << std::put_time(&time, "%Y %b %d %H:%M:%S %a");
timeS = ss.str();
std::cout << "You passoword: " << pass << std::endl;
writeFile(pass, company, timeS);
}
}while(input != -1);
return 0;
}

Answer 4

Just ignore everything after the internal while loop.
Ok. Let's do that...
int main()
{
int input;
do
{
std::cout << "Enter password length: ";
std::cin >> input;
while(input < 8 || input > 16)
{
std::cin >> input;
}
}while(input != -1);
return 0;
}
I know that the problem is somewhere in the while loop. I just don't see it.
I hope you see it now. Your inner while ensures that input is never -1.
I think your current problem is a symptom of not structuring your code. Hence, to fix your code I propose to use functions:
void do_something(int input);
bool read_and_validate(int& input) {
input = 0;
while(input < 8 || input > 16) {
std::cin >> input;
if (input == -1) return false;
}
return true;
}
int main() {
int input;
while( read_and_validate(input) ) {
do_something(input);
}
}