Why is exit(0); giving me a std:string... error? - c++

I'm new to C++. I decided to not watch the next tutorial and put my skills to use, by making a funny Mind Reader application. I'm pleased with myself, however, even though I've ironed out most bugs, I still have one concerning the exit function. I read the C++ documentation for it, and I'm not sure what I did wrong. I did exit(0);. I have a very weird error, which is:
no match for call to '(std::string {aka std::basic_string<char>}) (int)
I have searched online, however I am still unaware of what the problem is. My error is on line 59 (marked in the code):
#include <iostream>
#include <string>
#include <cstdlib>
using namespace std;
int main()
{
//declaring variables to be used later
string name;
string country;
int age;
//header goes below
cout << "#######################################";
" ############ MIND READER ############"
"#######################################\n\n";
//asks if the user would like to continue and in not, terminates
cout << "Would like you to have your mind read? Enter y for yes and n for no." << endl;
cout << "If you do not choose to proceed, this program will terminate." << endl;
string exitOrNot;
//receives user's input
cin >> exitOrNot;
//deals with input if it is 'y'
if (exitOrNot == "y"){
cout << "Okay, first you will need to sync your mind with this program. You will have to answer the following questions to synchronise.\n\n";
//asks questions
cout << "Firstly, please enter your full name, with correct capitalisation:\n\n";
cin >> name;
cout << "Now please enter the country you are in at the moment:\n\n";
cin >> country;
cout << "This will be the final question; please provide your age:\n\n";
cin >> age;
//asks the user to start the sync
cout << "There is enough information to start synchronisation. Enter p to start the sync...\n\n";
string proceed;
cin >> proceed;
//checks to see if to proceed and does so
if (proceed == "p"){
//provides results of mind read
cout << "Sync complete." << endl;
cout << "Your mind has been synced and read.\n\n";
cout << "However, due to too much interference, only limited data was aquired from your mind." << endl;
cout << "Here is what was read from your mind:\n\n";
//puts variables in sentence
cout << "Your name is " << name << " and you are " << age << " years old. You are based in " << country << "." << endl << "\n\n";
cout << "Thanks for using Mind Reader, have a nice day. Enter e to exit." << endl;
//terminates the program the program
string exit;
cin >> exit;
if (exit == "e"){
exit(0); // <------------- LINE 59
}
}
}
//terminates the program if the input is 'n'
if (exitOrNot == "n"){
exit(0);
}
return 0;
}
Thanks

The local variable exit shadows other identifiers from outer scopes with the same name.
To illustrate with a smaller example:
int main()
{
int i;
{
int i;
i = 0; // assign to the "nearest" i
// the other i cannot be reached from this scope
}
}
Since the only exit visible is an object of type std::string, the compiler sees exit(0) as a call to operator()(int) and throws a hissy fit when it doesn't find one among std::string members.
You can either qualify the name (std::exit(0);) or rename the variable. And since all of your code is in main you can simply say return 0; instead.

Try using return 0; or return EXIT_SUCCESS;. It's the exact same thing. Also, you can only input one word into a cin. Instead, use getline(cin, string name); If it still doesn't work, add a cin.ignore(); before your getline(cin, string name);, like this:
//stuff
string country;
cout << "Now please enter the country you are in at the moment:\n\n";
cin.ignore();
getline(cin, country);
//stuff
return 0;

The problem is arrising because you declared a standard keyword as the name of a local variable.
Now as the local variable is of type sting it is not able to take it as its value.

Related

Asking for conditional information in C++

Not sure how I was supposed to formulate the title.
I'm writing a program that asks for a students name, and if the name is not "stop", then it asks for a course name. If the course name is not "stop", it asks for a grade, then returns to ask for another course until the course name is "stop". Then it asks for another student and does the whole thing again until the student name is "stop". Then it prints all the students with their courses and grades.
Here is my code:
#include <iostream>
#include <vector>
using namespace std;
struct student{
public:
string name;
string course;
int grade;
}student_t;
void input(){
cout << "Please type the name of a student: " << endl;
getline(cin, student_t.name[i]);
if (student_t.name.compare("stop")){
break;
}
else {
cout << "Please type a course name: " << endl;
getline(cin, student_t.course);
if (student_t.course.compare("stop")) {
break;
}
else {
cout << "Please type the grade: " << endl;
cin >> student_t.grade;
}
}
}
int main() {
int i;
vector<student> input(i);
for (i = 0; i < 20; ++i){
student[i].input();
}
cout << student_t.name << " - " << student_t.course << " - " << student_t.grade << endl;
return 0;
}
It does not work at all..
I'm new to C++ so I dont really know why.
Any ideas?
I can give one or two recommendations.
Instead of checking if every step is wrong (i.e. equals "stop"), focus on what is right (i.e. what's the next things to read). From a mental perspective, I find it much easier to think about what has to be right for the program to progress as intended, as opposed to "What can go wrong here?" at every step. Your input() could then be (in pseudo code):
if (student_t.name is not "stop")
{
Read_course_name();
if (student_t.course is not "stop")
{
Read_grades();
// Done
return(StudentInfo);
}
}
// Ending up here means "stop" was typed so deal with that
// in a meaningful way
...
Take a look at https://en.wikipedia.org/wiki/Separation_of_concerns and then ask yourself, -Is the input() function really an input or are there more than one concern that coud be broken out in a separate function?
Cheers
/N

cin not accepting user input in C++

I'm a beginner in programming, and I'm trying to make a program that calculated how much radiation you've been exposed to throughout your life. For some reason, the 'cin' in my xray function doesn't accept user input, and just exits with code 0.
#include <iostream>
#include <conio.h>
#include <windows.h>
#include <stdlib.h>
#include <string>
#include <sstream>
using namespace std;
bool nearpowerplant;
int XRay; // the amount of times you got an x-ray
double tRads = 0; // your total dose of radiation in your lifetime, measured in mSv (millisievert)
int age;
//the sleep function
void sleep() {
Sleep(1000); // 1000 miliseconds = 1 second
}
/*
>system("CLS")< for clear the console
*/
//introduction and pretty much the menu
void intro() {
cout << "Welcome to the Radiation Level Calculator" << endl;
sleep();
cout << "Conceptualized and created by Anatoly Zavyalov" << endl;
sleep();
cout << "Press the ENTER key to begin." << endl;
cin.get();
}
//introduction to general questions
void genintro() {
// intro to the medical
system("CLS");
sleep();
cout << "Let's begin with general questions." << endl;
sleep();
cout << "Press the ENTER key to continue." << endl;
cin.get();
}
//medical questions
void Age() {
//age
system("CLS");
cout << "How old are you?\n" << endl;
sleep();
cin >> age;
if (age <= 0) {
cout << "Your age can't be less or equal to 0." << endl;
Age();
}
else {
tRads += (age * 2);
sleep();
cout << tRads << endl;
}
}
//live close to powerplant?
void powerplant() {
system("CLS");
cout << "Do you live within 75 kilometers of a nuclear powerplant?" << endl;
sleep();
cout << "If yes, type YES. If no, type NO." << endl;
cin >> nearpowerplant;
if (nearpowerplant = "YES") {
tRads += (age * 0.01);
}
else {}
sleep();
cout << tRads << endl;
}
void xray() {
system("CLS");
cout << "How many times have you had an x-ray?\n" << endl;
sleep();
cin >> XRay;
if (XRay < 0) {
cout << "You can't have an x-ray a negative amount of times." << endl;
}
else {
tRads += (XRay * 3.1);
}
sleep();
cout << tRads << endl;
}
//main function, put all of the loops into here
int main() {
intro(); // the introduction
genintro(); // medical intro
Age(); // asks for age
powerplant(); // asks if lives close to powerplant
xray(); // asks for x-ray
return 0;
}
EDIT: I have edited the post to include the whole code. By the way, I am using Visual Studio Community 2017.
bool nearpowerplant;
nearpowerplant is a bool. It is true or false. That is it. It's worth noting that there is no reason for this variable to be globally accessible and consuming storage for the entire run of the program. It is used twice in the program, both times in the same function. It should be an Automatic variable scoped by the function that uses it.
cout << "If yes, type YES. If no, type NO." << endl;
cin >> nearpowerplant;
Reading "YES" or "NO" into a variable of type bool fails. cin cannot convert the string input into a boolean value and cin stops accepting input until the error is cleared. It's also a good idea to remove the garbage input that caused cin to fail or guess what? cin's just going to fail again. There are hundreds of SO questions on how to handle this, so I'm just going to drop keywords here: clear and ignore.
Takeaways: Make sure the data entry matches the type of the data being entered into and test the stream after every read to make sure the read succeeded.
eg:
if (cin >> nearpowerplant)
{
// do stuff
}
else
{
// clean up
}
This solves OP's visible error, but since it is heavily entwined with the next bug they are likely to find, we might as well cover it as well.
if (nearpowerplant = "YES") {
tRads += (age * 0.01);
}
else {}
if (nearpowerplant = "YES") { uses = (assignment) where it should use == (comparison). C++ is unforgiving here because this will compile. What it really did was takes the address of the string literal "YES", test that it's not null, and set nearpowerplant to the result. Since the address of the string literal is never going to be NULL, the result is always true, and when the if tests the result, the if will always enter.
Eg: http://ideone.com/4QL2jn
So what we need is something more like
cout << "If yes, type YES. If no, type NO." << endl;
string temp;
cin >> temp;
if (temp == "YES") {
tRads += (age * 0.01);
}
else {}
Note this will skip if the user inputs "yes", "y", "Yes" or anything other than exactly "YES". How you deal with this is up to you, but std::tolower and std::transform may help somewhat.
I think with sleep() comes undefined behavior, you should test it without, the os handles user-input and you do not have to care about the user typing in. endl flushes cout, so the text is directly shown.
Edit:
Maybe system("CLS") or sleep produces a silent error.

Safe [Y/N]; [1/2/3/etc.] function

I tried to make a an introduction to a "game", and in its functions I made some Yes/No, 1/2/3, situations.
Im new to this however it wasn't that difficult, worked perfectly. The problem appeared when handling with invalid inputs. So this is what the code looks like by now:
#include "Introduction.h"
#include "GameConstants.h"
#include "PlayerCharacter.h"
#include <iostream>
#include <windows.h>
using namespace std;
Introduction::Introduction()
{
}
/////////Function N.1///////////
void Introduction::presentation()
{
char confirm;
string enteredName;
cout << constants.line() << "Welcome traveler! What is the name?" << endl;
getline(cin,enteredName);// Gets the WHOLE LINE as the name.
while (confirm != 'Y') //If the player doesn't confirm the name with 'Y' in will run again until it does.
{
cout << constants.xline() << "Your name is " << enteredName << " right? (Y/N)" << endl;
cin >> confirm; //The player's answer
cin.sync(); //Only takes the first character
confirm = toupper(confirm); //Turns player message into CAPS for easier detection in the "if" statements
if (confirm == 'N'){ //If not the correct name, gives another chance
cout << constants.xline() << "Please, tell me your name again..." << endl;
cin >> enteredName;
cin.sync();}
if ((confirm != 'Y')&&(confirm != 'N')){ //If an invalid input is entered, gives another chance. And insults you.
cout << constants.xline() << "Fool Go ahead, just enter your name again." << endl;
cin >> enteredName;
cin.sync();}
}
if (confirm == 'Y'){ //When the answer is yes ('Y') /* Uneeded line */
PC.setName(enteredName); //Saves the name
cout << constants.xline() << "Excellent! I have a few more questions for you " << PC.name() << "..." << endl;
}
}
//////////Function N.2///////////
void Introduction::difSelection(){
int selectedDif = 0; //Variable to store selected difficulty whitin this function.
Sleep(2500);
cout << constants.xline() << "What kind of adventure do you want to take part in?" << endl;
Sleep(2500); //Wait 2,5 s
cout << "\n1= Easy\n2= Normal\n3= Hard" << endl;
while(selectedDif != 1&&2&&3){ //Selected option must be 1/2/3 or will run again
cin >> selectedDif; //Sets the user selected difficulty
cin.sync(); //Gets only first character
if((selectedDif != 1||2||3)&&(!(selectedDif))){ //If the input isn't 1/2/3 AND is an invalid character, this will run. And it'll start again
cout << constants.xline() << "Criminal scum. Go again." << endl;
cin.clear();
cin.ignore();
}
if(selectedDif != 1&&2&&3){ //If selected option isn't 1/2/3, this will run and will loop again. However I know this conflicts with the previous statement since this will run anyways.
cout << constants.xline() << "Wrong input, please try again." << endl;
}
else if(selectedDif == 1){
constants.setDiff(1);
constants.setStatPoints(15);
} else if(selectedDif == 2){
constants.setDiff(2);
constants.setStatPoints(10);
} else if (selectedDif == 3){
constants.setDiff(3);
constants.setStatPoints(5);}
}
}
The first function works perfectly you can type "aaa" or "a a a" and will work. However I'd like to know if there's a simpler way to do it. (Understandable for a beginner, just started 3 days ago lol; if it includes some advanced or less known code prefer to stay like this by now).
Now, the second one, I really have no idea how to fix it. I need something that if the user's input was an invalid character type, throw certain message, and if it's an int type, but out of the range, another message. And of course, run again if it fails. Did a lot of search and couldn't find anything that meet this requirements.
To check if the user input is an int, you could use the good() function.
int val;
cin >> val;
if( cin.good() ) {
// user input was a valid int
} else {
// otherwise
}
As for the range check, the syntax is a bit different.
This returns true if the number is not equal to 1 nor 2 nor 3:
selectedDif != 1 && selectedDif != 2 && selectedDif != 3
Another shorter way would be to use:
selectedDif < 1 || selectedDif > 3
Another thing, in c++, there are two keywords break and continue which will allow to reduce the code in the loops.

C++ Array not taking correct input from file

Disclaimer: I am a beginner to programming, so what I say might sound really stupid
I have to make a "Telephone Directory" for school. The program isn't complete, but there are some things that I need to fix before moving on. The array TelephoneNumbers either isn't storing the numbers from the file correctly, or isn't displaying them. For the SeaerchRecords function, the first number in the file is displayed correctly, the second is displayed as "2147483647," and the rest of the numbers display as "0." The modify function also doesn't change the number, and I confirmed this with the while in the function. The string array works perfectly fine, however. May someone explain what I'm doing incorrectly?
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
string TelephoneNames[100];
int TelephoneNumbers[100];
void ModifyRecords(); //Function to Modify Records
void SearchRecords(); //Function to Search Records
void DeleteRecords(); //Function to Delete Records
int main()
{
fstream inputFile;
fstream outputFile;
char choice;
inputFile.open("Telephone Names.txt"); //To store
for (int count=0;count<100;count++) //file names
{ //into a
inputFile >> TelephoneNames[count]; //string
}
inputFile.close();
inputFile.open("Telephone Numbers.txt");//To store
for (int count=0;count<100;count++) //file #'s
{ //into a
inputFile >> TelephoneNumbers[count];//string
}
inputFile.close();
//Display options available
cout << " Hello, do you want to:\n";
cout << " ======================\n";
cout << "-Modify Records|Enter M\n";
cout << "-Search Records|Enter S\n";
cout << "-Delete Records|Enter D\n";
//Store choice
cin >> choice;
//Send to different function
if (choice=='M'||choice=='m')
{
ModifyRecords();
}
if (choice=='S'||choice=='s')
{
SearchRecords();
}
return 0;
}
void ModifyRecords()
{
string name;
string newname;
int newnumber;
int count=0;
cout << "Enter the name of the person: ";
cin >> name;
for (count=0;TelephoneNames[count]!=name;count++)//To determine where in the strings the new numbers need to be
{
}
cout << "Enter the new name of the person: ";
cin >> newname;
cout << "Enter the new number of the person: ";
cin >> newnumber;
TelephoneNames[count]={newname};
TelephoneNumbers[count]={newnumber};
count=0;
while (count<6)
{
cout << TelephoneNames[count] << endl;
cout << TelephoneNumbers[count] << endl;
cout << endl;
count++;
}
}
void SearchRecords()
{
string name;
int count=0;
cout << "Enter the name of the person you would like to find: ";
cin >> name;
for (count=0;TelephoneNames[count]!=name;count++)//To determine where in the strings the new numbers need to be
{
}
cout << "Name: " << TelephoneNames[count] << endl;
cout << "Number: " << TelephoneNumbers[count] << endl;
}
Since there is no any answer still and I don't see exactly the problem at this point I'll provide some suggestions how you can find a problem in your code.
In any programming situation when you can't find a bug, first task is to locate it as much precisely as you can and check all input data and assumptions. Usually, debugger is used for such purposes, but you can just output text in console before creating final version of your program.
To start with, you must check that you really received names and telephones from your file:
inputFile.open("Telephone Names.txt"); //To store
for (int count=0;count<100;count++) //file names
{ //into a
inputFile >> TelephoneNames[count]; //string
cout << TelephoneNames[count] << endl; //WE MUST SEE WHAT IS REALLY STORED IN TelephoneNames
}
inputFile.close();
inputFile.open("Telephone Numbers.txt");//To store
for (int count=0;count<100;count++) //file #'s
{ //into a
inputFile >> TelephoneNumbers[count];//string
cout << TelephoneNumbers[count] << endl; //WE MUST SEE WHAT IS REALLY STORED IN TelephoneNumbers
}
inputFile.close();
Ok, when it is checked and you are defenitely sure there is no problem in your data we can move to SeaerchRecords function doing the same procedure. We must check what is happening while you are searching:
for (count=0;TelephoneNames[count]!=name;count++)//To determine where in the strings the new numbers need to be
{
cout << "Search step: " << count << " name " << name << " found name " << TelephoneNames[count] << " number " << TelephoneNumbers[count] << endl;
}
Doing so you will locate your bug rather quickly. The problem can be in input files format, in difference of "name" and stored names format etc.
I'll provide several additional suggestion how you can improve your code.
1) Try to use const declarations for such commonly used things as number of records (const int NUMBER_OF_RECORDS = 100; insted of just putting '100' everywhere), it will reduce the amout of work and possible bugs. 2) Try to check all possible problems that you program can encounter if someting is wrong with data. What will happen if you have less than 100 records in your files now? Program crush or silent reading of unappropriate data which is even worse. Check that you haven't reach file end on any step of reading along with current check that you've reached you number of records and do something in case of unappropriate data.
3) Check the possible problems with conditions in your cycles not to run them infinite number of times. Now your condition for(count=0;TelephoneNames[count]!=name;count++)
will execute forever if there is no such name or just crush the program on count 100 or more. You should check that count doesn't exceed that value. Good luck!

Writing a first and last name readable over 2 file matching programs

I'm writing a file matching program for a project for school. The idea is that one program allows you to enter info as follows: 1000 (acct number) Jane Doe 54.50 (balance). Then allow you to enter the account number and a transaction amount for the second program to combine and update a new master file.
The programs are working together just fine (the second one takes information from the first, including any transactions and updates the new balance - searching by account number) but the problem I am running into is with the name.
---Wasn't clear here. When I ask for a name and I put in a single string of characters, the program works fine, if I try to put in a full name, like Jane Doe I go into the loop mentioned below.
I've tried char name[20] which puts me into an infinite loop and I have to 'x' out of the program and I've tried assigning first and lastName to string. That worked for the writing but the program that takes the input file oldMaster and the transaction file inTransaction then outputs a new file newMaster, doesn't recognize the name.
I've tried getline also which isn't working for me, probably programmer error.
Should this be done as an array, if that's possible for this? I think I'm getting hung up on the fact that I am editing files. Answers are fine - but I like to figure it out on my own, just looking for a little guidance on where to go from here.
Hopefully this was fairly clear - if not I'll be happy to explain again in a different way. Just frustrated that I'm this close and can't solve it.
Thanks in advance!
#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <cstdlib>
#include <iomanip>
using namespace std;
void createOldMaster()
{
ofstream oldMaster;
int accountNum;
double balance;
char name[15];
oldMaster.open("oldmast.dat", ios::out);
if(!oldMaster)
{
cout << "Unable to open the file." << endl;
exit(1);
} // end if
cout << "Enter the account number (0 to exit)." << endl;
while(true)
{
cout << "Account Number: ";
cin >> accountNum;
if(accountNum == 0)
break;
else
{
\\ This is where it hangs up if I use a first and last name
cout << "\nName: ";
cin >> name;
cout << "\nBalance : " << endl;
cin >> balance;
oldMaster << accountNum << " " << name << " " << balance << endl;
}
}
} //end createOldMaster
void createTransaction()
{
ofstream inTransaction;
int accountNum;
double balance;
inTransaction.open("trans.dat");
if(!inTransaction)
{
cout << "Unable to open the transaction file." << endl;
exit(1);
}
cout << "Enter the account number and balance (0 to exit): " << endl;
while(true)
{
cout << "Account Number: " << endl;
cin >> accountNum;
if(accountNum == 0)
break;
else
{
cout << "Balance: " << endl;
cin >> balance;
inTransaction << accountNum << " " << balance << endl;
}
}
} //end createTransaction
int main()
{
createOldMaster();
createTransaction();
return 0;
}
Your best bet is to use as much of the standard C++ library as you can. Have a reference handy, maybe even a copy of the C++ standard if you're so inclined, and look for shortcuts to make your work easier and your code shorter.
Avoid primitive arrays and primitive strings wherever possible. Instead of primitive arrays try to use std::vector. Instead of primitive strings try to use std::string. Instead of C's FILE* try to use std::ofstream and std::ifstream. If you need to prohibit two accounts with the same account number then choose a C++ container that guarantees unique elements. If you need to find an element in a container try to use a member function of the container for the search, and if that doesn't exist then a standard search function from the standard C++ algorithms.
Reuse and steal mercilessly.