C++ :: How To Improve Validity Check For User Input
Apr 24, 2013
I wonder how can I improve my validity check for user input? I only want them to key in certain range of digit.
Also for my validity check, when I key in character such as ABC, it lead to infinity loop
Here is my code : Code: /*Write a program that can calculate user's age by getting user input their birth date.*/
#include "stdafx.h"
#include <iostream>
#include <time.h>
using namespace std;
int main()
{
int yyyy, mm, dd; //year, month, day
int i = 0; //for the sake of validity check
[Code]...
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Feb 5, 2013
I'm trying to write a short program that takes the input from a user and trims any leading/trailing white space, and then checks how many words are in the string. Problem is, I'm only allowed to use stdio.h and stdlib.h. How can I accomplish this? Also, how would I check if any of the characters which were entered aren't either a number, letter, or '-'?
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Jun 9, 2014
How do I error check if the user is inputting letters and not numbers? For example, if the user inputs "Lab.txt" I need to display an error message. If they input "Lab2part2.txt" then this is correct and what I want.
I've found a lot of information online on how to error check for numbers or a single letter (EX: 1,2,3, etc. or 'A' 'B' 'C') but nothing for actual WORDS or maybe I should refer to it as a string of characters?
Is there any way to do this? Because my program requires I ask the user to input the name of the file. But the way my code is currently set up is even when the user inputs the wrong file name it still opens the file. I want to prevent this from happening so my thought was to error check user input.
/*Program to determine company's weekly payroll*/
#include <iostream>
#include <string>
#include <fstream>
using namespace std;
void OpenTheFile() {
ifstream inputFile;
string filename;
char letter;
int number;
[Code] .....
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Jul 23, 2014
This works, if just loops through till it doesn't find a space or tab than counts the index at that point then uses substr to get rid of any spaces/tabs, it's a small function and uses a goto. how to do it?
Code:
string trimLeft(string lineOfCodeToTrim){
string l = lineOfCodeToTrim;
int k =0;
for(UINT i = 0;i<l.length();i++){
[Code] ....
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Mar 23, 2014
Code:
#include <stdio.h>
#include <stdlib.h>
#define MAX_READ 2
int main( ) {
char * secret = "abecedarium consisting This is a string literal!";
[Code] ....
I am trying to test what happens in the sscanf converted types (command and string) if they are smaller, i got surprised that the printf worked, so i dont know why.
this code is just a test for what i want to do, what i really want to do is for example: i have this string from the stdin which must have the following format:
connect name.surname
So I need to check the cases when it is not the input that i want, namely if the name.surname is for example bigger than 30 chars. and also if it has the abecedary characters from the ascii...
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Sep 19, 2013
I'm building a cross-platform library which links to some other 3rd party libraries at run time (i.e. on Windows, the other libs will be available as DLLs whereas on Linux / OS-X etc they'd be shared objects, which are similar). For the sake of argument, one of those libraries is called "jack".
Obviously, our app can't guarantee which version of the other libs will be on the user's system (or even that they'll be installed at all). So our code is littered with statements like this:-
Code:
if (!jack_port_type_get_buffer_size) {
warning << _("This version of JACK is old - you should upgrade to a newer version") << endmsg;
} else {
some_var = jack_port_type_get_buffer_size();
}
We link to the latest version of jack, where that symbol is declared like so:-
Code:
size_t jack_port_type_get_buffer_size();
One problem is that it doesn't even seem to be an exported symbol (although that wouldn't affect the other platform builds). But apart from that, our customer might have an old copy of jack installed or even no copy! We seem to be making the assumption that if our customer has an up-to-date version, jack_port_type_get_buffer_size will be set to a valid address - but in all other case it'll be magically set to zero (there's nothing in our code that sets it to zero).
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Feb 10, 2013
How can you tell what button(yes/no) on a message box is clicked? Below is what I have right now but I am getting errors.
if (MessageBox(NULL,"The Message", "The Title", MB_YESNO) == IDYES){
do something
}
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Apr 27, 2013
Code:
char value;
printf_s("enter:");
if (scanf_s("%c", &value) != 1)
{
printf_s("oppppssss
");
}
else
{
printf_s("ok");
}
I wanted to check whether the input is a character or not, if a character is given then the output suppose to be "ok", but the output is always "oppppssss", where is the problem here?
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Mar 20, 2013
Description: This program asks the user to enter a Fahrenheit temperature and then converts it into Celsius and Kelvin temperature.
Code :
#include <stdio.h>
void Temperatures(double temp_F);
int main(void) {
double temp;
[Code]...
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Jan 15, 2013
I have an assignment to do..i have done it..but i need to do one more thing. Things sound like this: user inputs 6 integers program needs to check them if there are integer if not it has to output a message for the user if the input is integer it has to go further and work with the input. I have used this structure :
if ( ! ( cin >> temp ) ) {
cout<<"Input is not integer.This program will end ! "<<endl<<endl<<endl;
system("pause");
return 0;
}
Where I declared temp as being int since i started, the problem is after it gets the last input still waits for an input i will attach the source code if needed.
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Mar 20, 2014
I've been trying to finish this airplane seating program I've been working on for a month or two. The problem I have right now is that if the user inputs a number when prompted to enter the column letter he wants, the program goes on to the next step as if the prompt had been answered correctly.
So I originally used string but I heard from Daleth that Char was better, but I don't know how to apply it. I figured out cin.fail, but I've yet to finish this part.
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Dec 22, 2012
Goal: To allocate some memory as a char*, read in some binary data, re-interpret it as a float* and then free the memory.
My code looks like:
void someFunction(float* &result) {
char * tmp = new char[1000];
//...Fill the char buffer here...
result = (float*)tmp; //Reinterpret binary data as floats
[Code] ....
Is the cast back to char* necessary on the red line (or could I have validly left it as float*)? Would it be different if I had written char * tmp = (char*)malloc(sizeof(char)*1000); on the blue line (and correspondingly used free (char*)floatData on the red line?
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Nov 3, 2013
I have a homework that needs to verify if the input of the user is an integer using only loops no if statements Here's the problem:
A program is required that prompts the user for a number. The program will then print a series of asterisks to represent the number. If the user enters a number less than 1, the program stops. For example:
Enter a number: 5
*****
Enter a number: 3
***
Enter a number: 9
*********
Enter a number: 0
All user input must be validated:
- Check for non-numeric input when reading numeric input
- Check that values entered are within the expected range for their purpose, or in range based on the requirements statement
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Jan 20, 2013
i'm making a for loop for a mini game which required the user to enter the input number.Let say if the user accidently entered a character instead of integer the whole program will go haywire so is there anyway to check for the error and prompt the user to input the data again?Here is the simple program...
for(row=0;row<4;row++)
{
printf("Enter Row%d:",row);
for(col=0;col<4;col++)
{
scanf("%d",&num[row][col]);
}
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Jun 10, 2013
I need a function to check if the inputted string contains a colon. It has to be in an if loop as the condition.
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Nov 8, 2013
This program works but i need to build an additional loop that will re-prompt a user if his initial entry (int y_n) is other than 'Y', 'y', 'N', 'n'. For instance if a user tries to enter 'Yup', he will be prompted "That isn't a valid entry" and then re-asked to enter int y_n.
Note: If user answers Y he is asked to enter a value that is entered into an array. If the user at any point answers N, the program ends and final stats are cout.
#include <iostream>
using namespace std;
int main(){
char y_n;
int i = 0;
float input_value;
float myarray[100];
[Code] .....
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Oct 16, 2013
If I have a char array that that looks like
char array[] = {'a', 'b', 'c'};
How can I check user input against all of these values at once?
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Oct 8, 2014
In my WinForm, Our client insists to use Textbox instead of DateTimePicker field, and they want to input in ddmmyy format.
Using Visual Studio 2010 C# 4.0.
PC date time setting: GMT +08:00 dd-MMM-yy.
Assumed today date is 291014 (29-Oct-14).
CodeBehind:
DateTime inputDate;
// the WinForm allows user to input date not earlier than 2 years before today date and not more than 1 months from today date too.
//Assumed I input date as 261014 (26-Oct-14)
if(DateTime.TryParseExact(input, "ddMMyy", new System.Globalization.CultureInfo("en-US"), System.Globalization.DateTimeStyles.None, out inputDate)) {
DateTime minDate = DateTime.Now.AddMonths(-24);//Assumed it is 29-Nov-14
DateTime maxDate = DateTime.Now.AddMonths(1);//Assumed it is 29-Oct-12
I tried many methods but none works (I have checked many threads/forums also).
//Method 1
if(inputDate >= minDate && inputDate <= maxDate)
return true
//Method 2: B return true but A ***always*** return false, Why??
if (inputDate >= minDate)
A = true;
[code]....
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Jun 20, 2014
I have been trying to make a very simply programme that checks if the inputted information is an integer or not (i.e: that it contains no other characters).
I have tried using the isdigit function (but this only works for single characters). I have tried cin.clear, cin.ignore (1000) but this doesn't work either..
Any effective way to check if x in the following programme has been entered correctly
#include <iostream>
using namespace std;
int main() {
cout << "Please enter an integer (positive or negative)" << endl;
int x;
cin >> x;
HERE I WOULD LIKE CODE TO CHECK IF THE USERS INPUT IS VALID
}
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Jun 19, 2014
How you can make a c++ program that checks to see if the user presses the power button on their computer? And if so, how?
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Dec 25, 2014
I'm trying to check to see if a string from standard input is alphanumeric or not. I feel as though there may be a function for this but...
Code:
for(test_pass = i; test_pass < i; i++){
if(test_pass[i] == ('1', '2', '3', '4', '5', '6', '7', '8', '9', '0'))
printf("Your password is alphanumeric!
");
}
The compiler wasn't too happy with this.
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Apr 11, 2013
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"?
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Nov 1, 2014
I am making program that allows the user to determine how big the array size will be and then asks the user to make up numbers to fill the array. Every time run the program on Dev C++ it says "program has stopped working"
Heres My Code:
//Assignment 19 Program 2
#include <iostream>
using namespace std;
int main()
[Code].....
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Feb 15, 2013
This code is supposed to ask the user to input characters at most 20 and they should only be composed of alphabets/spaces..
Code:
#include <string.h>
#include <stdio.h>
#include <ctype.h>
int main(){
char addressbook[6][30][0];
int current_record = 0, length, i=0;
[Code] ....
I have removed the error from the main code but there's still this lingering error in the return part.
syntax error before 'return'.
It won't compile.
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Oct 29, 2014
Write a program that will search soccer players data to check whether a name supplied by the user is on that list. For doing the search, the user may provide either the player’s full last name or one or more starting letters of the last name. If a matching last name is found, the program will display the player’s full name and date of birth. Otherwise, it will display “Not found”.
Requirements specification:At the start, the program will ask the user to enter information about 10 soccer players constituting soccer player data. Each soccer player data will consist of the following fields:
Last name
First name
Birth month
Birth day
Birth year
The user will be asked to enter each soccer player data on a separate line with the field values separated by a space.
Once the data is entered, the program will display a menu of choices as below:
Chose an option:
(1 – input data, 2 – display original data, 3 – sort data , 4 – display sorted data 5 – search by last name 6 – exit the program )
If the user chooses option 1, the program will ask the user for a data and populate the array of structures that will hold the data for each of the soccer players.
If the user chooses option 2, the program will display data in the order provided by the user (original data).
If use chooses option 3, the program will sort data by last name.
If user chooses number 4 the program will display the data sorted by last name.
If the user chooses option 5, the program will ask the user to enter one or more starting letters of the soccer player’s last name. It will then search the soccer player data for the matching last name. If a match is found, it will display the first player found with the matching pattern. If a match is not found, the program will display “Not found”. If the user enters two forward slashes (//) for the last name, it will no longer search for the name. Instead it will display the main option menu.
If the user chooses option 6, the program will display “Thank you for using this program” and will end.
Why my program isint executing correctly. Here is what i've so far . . . .
#include <iostream>
#include <string>
using namespace std;
struct data {
string lname;
string fname;
int birthmonth;
int birthday;
int birthyear;
[Code]...
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Jan 1, 2014
In this simple end-of-chapter problem, the ages of two people are to be compared and determine who's older. The problem I'm experiencing is that the second user name input is being skipped and going straight to the second users age.
So while running the program it looks something like:
What is user ones name?
<input name>
How old are they?
<input age>
What is user twos name?
How old are they?
<input age>
<if statement result>
Here's my code:
Code: #include <iostream>
#include <string>
using namespace std;
int user_one_age;
int user_two_age;
string user_one_name;
string user_two_name;
[code].....
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