deal with a failed input stream and type checking input?
I use:
cout << "
Enter a menu option: ";
while(!(cin >> menuGameMode))
{
cin.clear();
while (cin.get() != '
')
continue;
cout << "Enter a menu option: ";
}
Is this the "Best" way to do it?
EDIT: We're assuming input is expecting an int.
#include <cstdlib>
#include <stdio.h>
#include <string>
[Code]....
I'm trying to load a file input stream to load all the character content into a variable (say from a .java file for example), but for some reason whenever I type in the name of the file I want to stream I get the report: RUN FAILED (exit value 1, total time 2s)
I simply need to know how I could swap the first and last letters of the input in this program:
int main() {
cout << "---------------------------------------------------------" << endl;
cout << " Letter Swapping Program" << endl;
cout << "---------------------------------------------------------" << endl;
string word;
cout << "Please enter a word at least 3 letters long: ";
cin >> word;
[Code] ....
By all means, I know this is a messy program and is not the most concise way to write it....
Code:
#include <fstream>
#include <string>
using namespace std;
ifstream inf("file name");
string line;
while (inf.good()) {
getline(inf, line);
}
instead of line by line i want the complete data from file to the string.What modification i have to do?
I am trying to simplify my code by creating a function which takes an input then checks whether it is "y" or "n" then outputs either 1 or 0 depending on the input. So far this is what I have
int Choice(string choice) {
while(choice.compare("n") != 0 && choice.compare("N") != 0 && choice.compare("y") != 0 && choice.compare("Y") != 0){
cout << "Please enter a valid input either [y/n] : " << endl;
cin.clear(); cin.ignore(); cin >> choice;
[Code] ...
And I call it in the program using
cout << "Do you wish to change the hubble type of any galaxies? [y/n]" << endl;
cin >> choice;
while(Choice(choice) == 1){
....
cout << "Do you wish to change the hubble type of another galaxy? [y/n]" << endl;
cin << choice;
}
It compiles fine but displays some bizarre behaviour, I need to end the line twice in order for the program to continue and sometimes it just stops working (doesn't exit just appears to be stuck in a loop).
I am trying to extract unsigned values from an input stream. I expect the extraction to fail when an invalid character is extracted. It fails correctly when I try to extract an unsigned int from "abc", but when I try to extract an unsigned in from "-1", the extraction succeeds, and the max unsigned int value is extracted (as if -1 were cast to unsigned int). I would expect the '-' to cause the extraction of an unsigned value to fail.
The code I am using is below.
#include <iostream>
#include <sstream>
#include <string>
#include <limits>
int main() {
unsigned int value = 8;
std::string negString = "-1";
[Code]...
Is this standard behavior for an istream extractor?
I am trying this in both Linux (gcc 4.4.3) and in windows with Code::Blocks (whaterver came with CB 13.12, apparently gcc 4.7.1)
What is the traditional way to monitor a blocking subroutine that is using a file stream as its input? That is, what is the traditional way to make a progress meter in the console?
Say I have a function that takes in a filestream and works with it. Suppose this file stream has a position and length property like in C# FileStream:
Code:
void sub (filestream file)
{
//read a bit of the stream, which advances stream cursor position
//do something
//repeat until all of file stream has been used up
}
Presumably the function is chomping along the file stream as it is doing some calculations serially on the file stream.Because the function is blocking, there is no way to access the file streams position and length in this thread. So naturally it seems like the best thing to do to monitor the progress of that function is to make another thread and pass it the file stream object as a parameter, and in this separate thread, monitor the distance between filestream's position and length to determine how much of the file stream has been used up, and every second or so output the amount of file stream used onto the console.
I know that an int is usually 4 bytes, ranging from -2^31 to 2^31-1 for a signed int and 0 to 2^32-1 for an unsigned int. My question is simply, bit-wise (I know they are labelled in the code), how does it determine whether to show -2^31 or 2^32-1 if it was 11111111 11111111 11111111 11111111 in bits? Is there a 5th byte to tell the compiler what data type to treat the input as?
View 3 Replies View RelatedI'm currently trying to solve a programming assignment and i got the logic of it, however i find it hard to implement.
What i need to do basically is fill an array with objects. Each object is a class that contains only one type of data. This means i can place int, double and string for example in one simple array.
However i can't figure out how to read data and then decide what it is. Even if i use templates once i call the function i have to give it a type, so getType<int> for example will not work with double or string.
I know about typeID and how to use it, i just can't figure out where to use it.
Originally I had to create a simple integer palindrome program that looped while the user entered 5 digit inputs (entering -1 stopped the loop). I did this using a conversion to string, reading the length to determine if the length was valid, and then reading the string forward and backwards inside of a while loop. (snippet below)
while( digitsEntered != -1)//Allow user to quit by entering -1 to end the loop
{
ostringstream convert;//conversion stream
convert << digitsEntered;//converted text from number goes in the stream
convertedString = convert.str();//store the resulting conversion to convertedString
[Code] ....
The next stage of this program was to do the same thing with strings instead of integers. However, the option to end the loop by entering -1 is still a requirement.
I think the way to do this is to first determining whether the input is a string or an integer, and if it is a string then read it and if it's an integer determine if it's -1. However, whenever I write code to do this, it converts strings to 0 so the string is not stored and cannot be read to determine if it is a palindrome. Is there a way to determine the type of input without converting it into a different type i.e. read string and then keep string or read number and keep number?
How would I check for proper data type when someone is to input a value into the program? Ex:
int i;
string a;
cout << "Enter a number: ";
cin >> i;
cout >> "Enter a string: ";
cin >> a;
How would you check to make sure that int i would be an actual number and not a letter like "a"?
Here's my code so far:
Code:
#include <iostream>
#include <iomanip>
using namespace std;
int main() {
int dayNumber = 1;
[Code] ....
The code, when run, prompts the user to input an integer like this:
Code:
Day 1
Andy :>12
Bill :>7
Charlie :>15
Day 2
Andy :>5
Bill :>25
Charlie :>14
.
.
.
etc.
Ok, so the code prompts the user to enter an integer for each of the 3 persons and then increments the "Day" and so on... When the user enters a negative value (-1, -2, etc.), the loop is broken and the program ends. Alright, everything is hunky-dory so far. 2 things which I can't figure out.
1. when the user doesn't enter anything and just hits return, the cursor drops a line and is still awaiting an input but doesn't show the prompt "Andy :>", for example. How can I get it to repeat the last prompt when the user doesn't enter anything? Like:
Code:
Day 1
Andy :>
Andy :>
Andy :>12
Bill :>25
Charlie :>15
.
.
etc.
2. When the user enters a letter or a special character, the program blows up. How can I correct this?
I've tried changing the data type for the variable used for the input, tried using getline, get, etc. With my current beginner knowledge, I'm missing something. So how can I get this to work?
The program should allow only integers to be entered, while allowing a negative number to trigger the loop to break or the program to end, and while re-prompting the last person if the user entered an invalid input.
I cannot get my function overloading the input operator for rational type objects to work.
lab9.cpp: In function ‘std::istream& operator>>(std::istream&, const rational&)’:
lab9.cpp:186:20: error: invalid initialization of reference of type ‘std::istream& {aka std::basic_istream<char>&}’ from expression of type ‘rational’
return (inputFrac);
lab9.h
#include <iostream>
using namespace std;
class rational {
public:
rational();
rational(int a, int b);
[Code] ......
Assuming I have a list of pointers to a generic type T:
#include <vector>
//...
list<T*> myList;
Now assuming I want to go on the list, and if T's type is matched to the type I'm looking for, then cast it to this type and do something. List shown here:
list<T*>:: const_iterator iter= myList.begin();
for(; iter!=myList.end(); ++iter){
if( typeid(*iter)==typeid(Something*)) //RUN-TIME ERROR
dynamic_cast<Something*>(*iter)->DoSomething();
}
how do I fix this run-time error?
// this program gives random number output
#include <iostream>
#include <cstdlib>// contains function protype for rand
#include <iomanip>// for setw
using namespace std;
[code]....
what is the effect on output of program of different numbers input to the int data type named seed*/
Ok so I have this simple program that gets input from a user. I just want to put in a line of code to make sure that hte user can't type in something like "pizza" , I want to make it say that if the user puts in something that is NOT a number they will get a error back saying "Wrong! try again!" Here is my code :
#include <iostream>
using namespace std;
//Summation Program
//Function Prototypes
int get_num();
void compute_sum(int num, int &sum);
[Code] ....
Assume the user has already put in the number of students (hence my variables numStuds, which will most likely be irrelevant to my problem).
So suppose I have this:
void inputStudentInfo(string *names, int *movies, const int numStuds) {
for(int i =0; i < numStuds; i++) {
cout << "Enter student name: "; getline(cin, names[i]); read_string(names[i]);
[Code] ....
Then I have my data type checking function:
//Data-Type Checking for strings
string read_string(string Sname) {
while(!cin.good())
[Code] ....
I am getting errors. I know the problem I think is that I am trying to data type check for a string made up of pointers* with just a string but I don't know how I am supposed to check this?
I am trying to create a simple interface on console to allow to input some values to some variables. For ex:
int main() {
double a = 1.5;
double b = 2.5;
double c = 3.5;
string x;
[Code] ....
However, I want these three to display at the same time (now they display one by one), and in the console window I can move the cursor between input place of a, b and c with "arrow key" of keyboard.
I would just like to know what does
while( (c =getchar())!='
' && c !=EOF );
do ? and how it do it?
I have see it in a example to clear the input buffer for next input through scanf but does not know its working clearly.
it is used in this example :
Code:
#include<stdio.h>
struct linklist {
char value[20];
struct linklist *next;
};
struct linklist *head,*curr;
[Code] .....
Program is to add two fractions together like so..
This program adds fractions. ‘Y’ continues, any other key exits program
===================================================
Enter numerator 1 ==> 1
Enter denominator 1 ==> 3
Enter numerator 2 ==> 1
Enter denominator 2 ==> 6
1 1 1
--- + --- = ---
3 6 2
-----------------------------------------------------
Continue? Y or N! ==> n
My question is that i need each input to be a number.
if a character is entered i want it to output something like..
This program adds fractions. ‘Y’ continues, any other key exits program
===================================================
Enter numerator 1 ==> 1
Enter denominator 1 ==> a
You need to enter a number here.
Press any key to continue.
and then clear the part where the letter was entered.
This program adds fractions. ‘Y’ continues, any other key exits program
===================================================
Enter numerator 1 ==> 1
Enter denominator 1 ==>
I wrote a program that reads a list from a file and stores it in a string type vector. Now, I want the user to input a word so that the program can search the vector to see if that word already exists. I have used every possible way of reading input from the console and storing it in order to compare with the vector but it never results in a match. When I print the input string and the vector string they are exactly the same thing (or at least print to the console as if they were). I've tried using getline; using cin direct to a string var; using cin to a char array and then casting to string using string str(arr); I even added a newline at the end just in case and STILL I cannot get a match.
vector <string> currentSet; //read a list in from a file and has 9 items in it
cin.ignore();
string line;
getline(cin, line);
if(line == vector[0]){//if printed to console line is HEAT and vector[0] is HEAT
cout<<"match"<<endl;
}
I wrote a program to write text contents to file stream through fputs, the file stream address was changed in the middle of writing text content to the stream (11% text content have been put into the file stream), that cause the file stream pointer can be evaluated problem and raise exception on stream validation code in fputs library function, my question is what things could go wrong to make file stream pointer changed its address to something else or a NULL pointer if the file stream have not been flushed and closed.
View 5 Replies View RelatedI was just wondering how to deal with overflow. My code works for exponential when i put small numbers in like 2 and 3. So it would do 2^3 which would be 8. But if i try something like 2^44 then I just get 0.
View 2 Replies View RelatedI have some header files with generic functions. And in one of them, I define TRUE and FALSE. Recently I started using another header file and it defined TRUE and FALSE as well. That caused GCC to throw an error, and not compile. In my case I can put #IFNDEF around the values so that if it is already defined they don't get defined again, but is there a better way to handle duplicate names? I assume the case would be the same for duplicated functions, how does that get handled?
View 6 Replies View RelatedI've knocked up a rough C parser for the purpose of colourizing code into XHTML/CSS, which makes me feel fancy. However, it doesn't quite handle comments properly. I can't quite work out how to deal with the slashes. Plus I'm sure there are other places that it slips up that don't feature in my simple tests, so here you go:-
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define FLAG_OUTPUT1
#define FLAG_EVEN2
#define NUMKEYWORDS32
}
[code]....
current functions are:
char *createEnvironment(int width, int height, int numWoodChips);
void printEvrionment(char *environment, int width, int height);
need to be:
int* createEnvironment(int width, int height, int numWoodChips);
void printEvrionment(int* environment, int width, int height);
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
[Code]....