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I'm learning C++ and I think I have a good understanding of the basics so far. I wrote this program to take information from the console about a student, and then print it out in a simple tabular format.
The problem I'm running into is that for some particular reason, I have to getline() twice for input of the student's name, or otherwise it will be blank. For the life of me, I can't figure it out, and was wondering if someone else could help figure out why this bug is happening.
The bug occurs in function getstudentdata(), and the line is getline(cin, s.name); ... I have to have it twice, or other wise it will leave the name blank.
The error is present in both the visual c++ compiler, and the g++ linux compiler. Below is the sourcecode (which works). To see the bug in action, comment out the getline(cin, s.name); and compile/run the program. Thanks!
Sincerely,
Robert
/*
*******************************************************************************
* CSCI 202 Assignment 1b by Robert xxxxxx 03/02/2005 *
* Takes student information and displays in tab form + column for GPA *
*******************************************************************************
*/
#include <iostream>
#include <iomanip>
// #include <conio.h> // for getche() // conio.h not found on linux system
using namespace std;
/*
Design a program that takes in student information
(Name, Student-id, Year, Major, Grade in 201, Grade in 202)
and displays a nice tabular form of output with those values
AND another column for the GPA (Grade in 201 + 202 ) /2.
*/
struct studentdata // structure for holding student data
{
string name;
string id;
string major;
char g201;
char g202;
float gpa;
};
inline void clear_screen(void); // function prototype, this clears the screen
void robcenterout(string centertext); // function prototype, this centers text
void getstudentdata(studentdata& s); // getstudent() will allow me to get multiple students with an easy function;
char getgrade(void); // function prototype, this gets and validates gradeletter
float gradetofloat(char grade); // function prototype, this turns char to float
float calcgpa(char grade1, char grade2);// function prototype, this calculates GPA
void drawline(void); // function will draw line;
int main()
{
clear_screen(); // clear screen first
cout << endl << endl << endl; // add a few blank lines before showing title
robcenterout("+-------------------------------------+");
robcenterout("| Welcome to the Student Grade Report |");
robcenterout("| By Robert Eckman for CS202 |");
robcenterout("+-------------------------------------+");
robcenterout("This program will take student info ");
robcenterout("(such as name, id, major) and their ");
robcenterout("grades for CSCI 201 and CSCI 202 and ");
robcenterout("print in tabular format, inluding GPA. ");
drawline(); // draw seperator line
cout << "Please enter the number of students you wish to enter : ";
int numstudents;
cin >> numstudents; // input number of students
studentdata student[numstudents]; //create array of type studentdata
for (int i = 1; i <= numstudents; i++) // get info for students
{
clear_screen();
cout << "Please enter information about student " << i << " of " << numstudents << endl;
drawline();
getstudentdata(student[i-1]);
}
// below, we build the output for the program in tabular format
clear_screen();
drawline();
cout << setw(4) << "##";
cout << setw(25) << "Student name" << setw(9) << "ID";
cout << setw(9) << "Major" << setw(7) << "CS201";
cout << setw(7) << "CS202" << setw(7) << "GPA";
drawline();
// now we add the student data
for (int i = 1; i <= numstudents; i++)
{
cout << setw(4) << i;
cout << setw(25) << student[i-1].name << setw(9) << student[i-1].id;
cout << setw(9) << student[i-1].major << setw(7) << student[i-1].g201;
cout << setw(7) << student[i-1].g202 << setw(7) << student[i-1].gpa << endl;
}
cout << endl << endl;
} // main() is complete
inline void clear_screen(void)
{
// char a = 27u;
// cout << a << "[2J"; //clears the screen using ANSI escape sequence
system("cls"); // for windows
// system("clear"); // for linux
}
void robcenterout(string centertext)
{
int width;
width = ((80 - centertext.length())/2 + centertext.length());
cout << setw(width) << right << centertext << endl;
}
void drawline(void)
{
cout << setfill('-') << setw(78) << "\n";
cout << setfill(' ') << "\n" << left;
}
void getstudentdata(studentdata& s)
{
cout << "Please enter name of student : ";
getline(cin, s.name);
getline(cin, s.name); // for some weird reason, must have this line twice.
cout << "Please enter " << s.name << "'s student ID : ";
getline(cin, s.id);
cout << "Please enter " << s.name << "'s Major : ";
getline(cin, s.major);
cout << "Please enter grade for CSCI 201 : ";
s.g201 = getgrade();
cout << "Please enter grade for CSCI 202 : ";
s.g202 = getgrade();
s.gpa = calcgpa(s.g201,s.g202);
}
char getgrade(void)
{
bool gradeflag = false;
char grade;
while(gradeflag == false)
{
cin >> grade;
grade = toupper(grade);
// the code below will check to see if the grade is valid
if ((grade == 'A') || ( grade == 'B') || (grade == 'C') || (grade == 'D') || (grade == 'F'))
{
gradeflag = true; // if grade is a,b,c,d,f then valid flag = true
}
else
{
cout << "\nsorry, " << grade << " is incorrect, please try again : ";
}
} // end of while
return grade; // returns the char value at function's exit
}
float gradetoint(char grade)
{
switch(grade)
{
case 'A' : return 4.0; break;
case 'B' : return 3.0; break;
case 'C' : return 2.0; break;
case 'D' : return 1.0; break;
case 'F' : return 0.0; break;
}
}
float calcgpa(char grade1, char grade2)
{
float g1, g2;
g1 = gradetoint(grade1);
g2 = gradetoint(grade2);
return (g1 + g2) / 2; // calculate gpa and return float value
}
/// END OF PROGRAM
http://www2.uwsuper.edu/reckman
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maybe try flushing the standard input and outputs for that matter wouldn't hurt
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I just tried your advice... I put in:
cout << flush;
before the getline(cin, s.name); but unfortunately, it didn't seem to solve the problem. 
The only other input I took before getline(cin, s.name)was
cin >> numofstudents;
So... I decided to change that line from getline(cin, s.name); to cin >> s.name; and everything worked fined up until the point where I use getline(cin, s.id); Then it skips input again.
How would I go about to flush the input for getline();
Robert
http://www2.uwsuper.edu/reckman
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I found the solution...
By placing:
cin.ignore();
before the getline(), I don't have to use getline() twice. It took a lot of googling to find this out, since the answer doesn't seem so obvious:
http://p2p.wrox.com/archive/c_plus_plus_programming/2000-10/2.asp[^]
But I would like to thank John DeVito for helping me out on this. Thanks!
Sincerely,
Robert
http://www2.uwsuper.edu/reckman
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Ok. I have an MFC app in VC++ .net
I have several Edit control boxes that I want to type in a voltage (in the form X.XX). Then I want to be able to take the voltage I entered, do a analog to digital conversion for an 8-bit number.. so something like voltage * 256/5, round the number to the nearest int.. then convert the int to the unsigned char representation. Now I think this will have some problems because there are several non-printing characters from 0 to 255 so the conversion will not work. Right?
If this is wrong let me know! Hehe. This is the easy way for me to do this problem.
The second way I don't know how to do.. same thing except I want to convert to an unsigned short.
The function that I am ultimately sending this data to takes an (unsigned char *)
Any and all help would be greatly appreciated. Also I would rather have unmanaged code help. No System namespaces. hehe. Thanks
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Use GetWindowText to get the number (as a string) from the edit control.
Use strtod to convert the string to a double.
Do your calculation, whatever it is.
To round the number to the nearest int you have to add 0.5 then cast it to an int
int MyInt = (int)(MyDouble + 0.5); A simple cast always rounds down, so adding 0.5 gives the effect of rounding up.
You can do a cast from an int to a short or char, you will just lose some info if your int is too large a value. The non-printing characters only matter if you actually want to print them.
"You're obviously a superstar." - Christian Graus about me - 12 Feb '03
"Obviously ??? You're definitely a superstar!!!" mYkel - 21 Jun '04
Within you lies the power for good - Use it!
Honoured as one of The Most Helpful Members of 2004
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Well I don't want to print the characters out, they are just being used as a one byte representation so I can send that byte across a usb line and then do the opposite conversion, char to int to decimal. etc...
For some reason when I've done this before.. I dont get the right symbol.. or maybe I am..
In the debugger in VC++ the value shows up in its hex value and then it also shows the actually char.. and for the ones that I thought it wasn't working it was showing that weird square character....
Am I just stupid and its doing the conversion right its just not showing it for whatever reason? (ie cuz its a nonprinting). It also happened for a couple of values around the middle of 0-255 at about 128.. That's totally a printable character.. So I dunno.
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You only have to worry about the hex value. What the displayed character looks like depends on glyph the current font uses to display it. The square just means the current font does not have a glyph associated with that ascii character.
"You're obviously a superstar." - Christian Graus about me - 12 Feb '03
"Obviously ??? You're definitely a superstar!!!" mYkel - 21 Jun '04
Within you lies the power for good - Use it!
Honoured as one of The Most Helpful Members of 2004
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I posted a question yesterday, but I never got any answers. The original question was about resizing a grid when double-clicked on. I got that part working, but the grid is still not redrawing correctly... There are other controls on the CFormView that the grid is covering when it's resized (like it's supposed to), but these controls are still showing through the grid until I actually move a scrollbar, then the grid is on top correctly. I tried RedrawWindow(),Invalidate(),InvalidateRect(), and even SetWindowPos() with &wndTopMost, and it still shows the other textboxes through the grid when it's resized. When my grid is resized to fill the entire form I don't want any other controls to be visible until they double-click it again. Any help?
My articles
www.stillwaterexpress.com
BlackDice
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I suggest hiding the other controls. It should be a simple case of calling ShowWindow(SW_HIDE) on them. You can use GetWindow(GW_NEXT) to find the other controls.
Stability. What an interesting concept. -- Chris Maunder
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that's what I ended up doing. I used EnumChildWindows() with this function:
BOOL __stdcall MyHideWindow(HWND hwnd, LPARAM lparam)
{
BOOL* pbVisible = (BOOL*)lparam;
CWnd *pWnd = CWnd::FromHandle(hwnd);
int nCurrentID = pWnd->GetDlgCtrlID();
if(nCurrentID != IDC_PROJECT && nCurrentID != IDC_PROJECTSTATIC &&
nCurrentID != IDC_VIEWSTATIC && nCurrentID != IDC_FILTER &&
nCurrentID != IDC_CUSTOM1 && nCurrentID != IDC_TEST)
{
int nCmdShow = (*pbVisible ? SW_SHOW : SW_HIDE);
pWnd->ShowWindow(nCmdShow);
}
return TRUE;
}
then send it in a true or a false for which one I want to do, leaving certain controls alone.
My articles
www.stillwaterexpress.com
BlackDice
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I need to play a WAV file when a push button is pressed, I did try the Wave Class for Playing and Recording Wave Files class on this site but complained about the my WAVs being invalid format.
Any simple examples out there that work for VS 7.1
Many thanks.
grahamfff
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PlaySound[^]
"You're obviously a superstar." - Christian Graus about me - 12 Feb '03
"Obviously ??? You're definitely a superstar!!!" mYkel - 21 Jun '04
Within you lies the power for good - Use it!
Honoured as one of The Most Helpful Members of 2004
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At the very least, make sure PlaySound can play your WAV files.
Maybe they ARE in an invalid format, or you are not setting up the format information correctly prior to using the WAV play class.
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I have a problem with the free instruction under win32, t raise an error when i try to free allocated memory after i allocated it with malloc, i don't know why, if the MSDN indicates that is right.
The code i use is some like this:
LPSTR lpCode=(char *)malloc(MAX_PATH);
strcpy(lpCode,lpText);
SendMessage(GetDlgItem(hMain,IDE_RTFBOX),WM_SETTEXT,NULL,(LPARAM)lpText);
free(lpText);
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I have no idee why you're allocating memory for a variable you don't use, but when you use malloc on lpCode you should use free on lpCode too. Not on lpText, which is a totaly different variable...
Wout Louwers
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Excuse me i forgot these lines:
char lpText[]="Hello world";
...
free(lpCode);
When i free the memory allocated in lpCodeit raise an error
The first example code was wrong excuse me.
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But the line
free(lpText);
does that exists in your code? Beacause that line is wrong. Please try your code without that line...
Wout Louwers
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You should try
lpText=(char*)malloc(32);
strcpy(lpText,"Hello world\n");
...
free(lpCode);
free(lpText);
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SendMessage is synchronous. It's perfectly OK to use lpText as the parameter. SendMessage will not return until the receiving window has handled the message.
If you wrote the control with ID IDE_RTFBOX, and overrode WM_SETTEXT, you should make a copy of the argument there.
Stability. What an interesting concept. -- Chris Maunder
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Anyone know how to turn it off from a WinInet-based client?
I'm getting hit by Q263754: WinInet Application Stops Responding and Shows 100-Percent CPU Utilization[^]. The problem only occurs when chunked encoding is enabled.
They recommend that you use HTTP 1.0, which doesn't support chunked encoding, except that specifying HTTP 1.0 in the request doesn't fscking work!!![^]  
Their recommendation is to change a setting in the registry to force IE/WinInet to use HTTP 1.0. It would, of course, be extremely poor form for my application to do this so is there anything else I can do?
I tried setting a "Transfer-Encoding: identity" header in my request but that causes the HttpSendRequest() call to hang 
Lets be honest, isn't it amazing how many truly stupid people you meet during the course of the day. Carry around a pad and pencil, you'll have twenty or thirty names by the end of the day - George Carlin
Awasu 2.1 [^]: A free RSS reader with support for Code Project.
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I have a proplem when I insert data into a binary field of table.
I use ODBC and MFC.
thank you very much.
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In my quest for a simple to use image loading library I came across GDI+. I only want to use the portion of GDI+ that loads images, since it loads every image type that I would ever need into a DIB (which I can extract and feed OpenGL). However, I have the most annoying and frustrating issue: the image is not loaded and the lastResult member of the Bitmap object indicates InvalidParameter. Obviously I'm feeding it something bad. The relevant code snippet follows:
<br />
xBoolean xImage::Load (char *fileName, xBoolean mipmap)<br />
{<br />
BitmapData *bmpData = new BitmapData ();<br />
Rect *rect = new Rect ();<br />
sint32 format, stride;<br />
uint32 i, j;<br />
xbyte *tempBuffer;<br />
uint32 wideLen;<br />
WCHAR *fileNameW = NULL;<br />
<br />
if (fileName == NULL)
return xfalse;<br />
<br />
wideLen = MultiByteToWideChar (CP_ACP, MB_PRECOMPOSED, fileName, -1, NULL, 0);
fileNameW = (WCHAR *)malloc (wideLen);
MultiByteToWideChar (CP_ACP, MB_PRECOMPOSED, fileName, -1, fileNameW, wideLen);
<br />
Bitmap bmp ((const WCHAR *)fileNameW, FALSE);<br />
<br />
...<br />
The string fileName is being properly translated to fileNameW as below:
<br />
fileName[0] 119 'w' char<br />
fileName[1] 104 'h' char<br />
fileName[2] 105 'i' char<br />
fileName[3] 116 't' char<br />
fileName[4] 101 'e' char<br />
fileName[5] 46 '.' char<br />
fileName[6] 116 't' char<br />
fileName[7] 103 'g' char<br />
fileName[8] 97 'a' char<br />
fileName[9] 0 char<br />
<br />
fileNameW[0] 119 unsigned short<br />
fileNameW[1] 104 unsigned short<br />
fileNameW[2] 105 unsigned short<br />
fileNameW[3] 116 unsigned short<br />
fileNameW[4] 101 unsigned short<br />
fileNameW[5] 46 unsigned short<br />
fileNameW[6] 116 unsigned short<br />
fileNameW[7] 103 unsigned short<br />
fileNameW[8] 97 unsigned short<br />
fileNameW[9] 0 unsigned short<br />
The constructor for the Bitmap object is as follows:
<br />
class Bitmap : public Image<br />
{<br />
public:<br />
friend class Image;<br />
friend class CachedBitmap;<br />
<br />
Bitmap(<br />
IN const WCHAR *filename,<br />
IN BOOL useEmbeddedColorManagement = FALSE<br />
);<br />
Recall that the lastResult member is being set to InvalidParameter. Here are the possible GDI+ return values:
<br />
enum Status<br />
{<br />
Ok = 0,<br />
GenericError = 1,<br />
InvalidParameter = 2,<br />
OutOfMemory = 3,<br />
ObjectBusy = 4,<br />
InsufficientBuffer = 5,<br />
NotImplemented = 6,<br />
Win32Error = 7,<br />
WrongState = 8,<br />
Aborted = 9,<br />
FileNotFound = 10,<br />
ValueOverflow = 11,<br />
AccessDenied = 12,<br />
UnknownImageFormat = 13,<br />
FontFamilyNotFound = 14,<br />
FontStyleNotFound = 15,<br />
NotTrueTypeFont = 16,<br />
UnsupportedGdiplusVersion = 17,<br />
GdiplusNotInitialized = 18,<br />
PropertyNotFound = 19,<br />
PropertyNotSupported = 20<br />
};<br />
It isn't that it can't find the file, GDI+ is initialized properly, and it isn't any useful error. One other thing, if I change the line
<br />
Bitmap bmp ((const WCHAR *)fileNameW, FALSE);<br />
to read
<br />
Bitmap *bmp = new Bitmap ((const WCHAR *)fileNameW, FALSE);<br />
the compiler spits an error about not finding the constructor, which I found odd. If anyone can help, it would be much appreciated.
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jgeorge21 wrote:
fileName[5] 46 '.' char
fileName[6] 116 't' char
fileName[7] 103 'g' char
fileName[8] 97 'a' char
From MSDN:
[quote]
Bitmap::Bitmap(filename, useIcm)
Creates a Bitmap object based on an image file.
Bitmap(
const WCHAR* filename,
BOOL useIcm
);
Parameters
filename
[in] Pointer to a null-terminated string that specifies the path name of the image file. The graphics file formats supported by GDI+ are BMP, GIF, JPEG, PNG, TIFF, Exif, WMF, and EMF.
[/quote]
I do not see tga in the list of supported formats.
Try http://www.codeproject.com/bitmap/cximage.asp[^] instead.
"You're obviously a superstar." - Christian Graus about me - 12 Feb '03
"Obviously ??? You're definitely a superstar!!!" mYkel - 21 Jun '04
Within you lies the power for good - Use it!
Honoured as one of The Most Helpful Members of 2004
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