C++, program outputs invalid input but continues through loop - c++

Question

I am trying to write a program which calculates the cost of a call based on the time the call was made, the day of the week and length of call. It has to be all call-by-value functions and output a option to repeat the program.
My problem is when I enter a invalid input for time such as a:37, it outputs invalid input but continues to the day input instead of returning to time entry. I am a new programmer and have tried everything I can think of to fix it but it either gets stuck in a infinite loop of exits the entire program.
Thanks in advance for any help!
#include <iostream>
using namespace std;
bool validateUserInputTime(int,char,int);
bool validateUserInputDay(string);
bool validateUserInputCallLength(int);
double calculateTotalCost(int,int,string,int);
string days[]={"Mo" , "Tu" , "We" , "Th" , "Fr" , "Sa" , "Su"};
float cost,fcost;
int main()
{
int hour;
int min;
int time;
char colon;
char answer = 'y';
string day;
string s;
bool result;
while(answer =='y')
{
cout<<"Enter the time the call starts in 24-hour rotation: "<<endl;
cin>>hour>>colon>>min;
result=validateUserInputTime(hour,colon,min);
if(cin.fail())
{
cout << "Invalid time input."<<endl;
cout<<"Please try again."<<endl<<endl<<endl;
cin.clear();
}
day=validateUserInputDay(s);
if(cin.good())
{
cout<<"Enter the first two letters of the day of the week:";
cin>>day;
}
cout<<"Enter the length of the call in minutes:"<<endl;
cin>>time;
result=validateUserInputCallLength(time);
if(result==0)
{
cout<<"Invalid minute Input."<<endl;
cout<<"Please try again."<<endl<<endl<<endl;
continue;
}
fcost= calculateTotalCost(hour,min,day,time);
cout<<"Cost of the call: $" << fcost<<endl;
cout<<"Do you want to repeat the program?";
cin>>answer;
}
return 0;
}
bool validateUserInputTime(int hour1,char ch,int min1)
{
if (cin.fail())
{
cout << "Invalid time input."<<endl;
cout<<"Please try again."<<endl<<endl<<endl;
cin.clear();
}
if(hour1 < 0)
{
return false;
}
if(min1 < 0)
{
return false;
}
if(ch!=':')
{
return false;
}
else
return true;
}
bool validateUserInputDay(string s)
{
int next=0;
for(int i = 0; i < 7; i++)
{
if(days[i] == s){
next=1;
}
if(cin.fail())
{
cout<<"Invalid day inpuT."<<endl;
cin.clear();
}
}
if(next==1)
{
return true;
}
else
{
return false;
}
}
bool validateUserInputCallLength(int time2)
{
if(time2<0)
{
return false;
}
else
{
return true;
}
}
double calculateTotalCost(int hour3,int min3,string d,int time3)
{
if((d=="Sa")||(d=="Su"))
{
cost=0.15*time3;
}
else
{
if((hour3>=8)&&(min3<18))
{
cost=0.40*time3;
}
else
cost=0.25*time3;
}
return cost;
}

Answer 1

Try using a loop. The loop will stop the program from progressing until the result value is true.
result = false;
while (!result)
{
cout<<"Enter the time the call starts in 24-hour rotation: "<<endl;
cin>>hour>>colin>>min;
result=validateUserInputTime(hour,colin,min);
}
You also forgot to put a false return statement on validateUserInputTime. Inputting non-digit characters might also crash the program, and cin.ignore happened to fix it.
if (cin.fail())
{
cout << "Invalid time input."<<endl;
cout<<"Please try again."<<endl<<endl<<endl;
cin.clear();
cin.ignore();
return false;
}

Answer 2

If you want to parse what the user entered do something like this instead
std::string time;
std::getline(std::cin, time);
now check if there is a ':' auto pos = time.find(':'); if (pos != -1) {}
then take out the hour part time.substr(0,pos)
then the minute part time.substr(pos+1)
then check if they are valid hour and minutes using e.g. stoi().
also it is better to do {} while () instead of while (answer == 'y') {...}