Good afternoon, I'm facing a problem on my c code and I don't know what is causing it.
Every time I try to print characters like these: "┌──┐" my program simply prints some strange characters, like on this screenshot:
I'm using Qt Creator on Windows, with Qt version 5.5.0 MSVC 64 bits. The compiler is the Microsoft Visual C++ Compiler 12.0 (amd64).
I tried changing the locale but with no success. The only way I found to print these characters was to define them as int variables with the ASCII code and printing them, but it led to some really extensive and ugly coding, like this:
int cSupEsq = 218; //'┌'
int cSupDir = 191; //'┐'
int cInfEsq = 192; //'└'
int cInfDir = 217; //'┘'
int mVert = 179; //'│'
int mHor = 196; //'─'
int espaco = 255; //' '
int letraO = 111; //'o'
//Inicia limpando a tela da aplicação
clrscr();
//Linha 1
printf("%c", cSupEsq);
for (i = 1; i < 79; i++) { printf("%c", mHor); }
printf("%c", cSupDir);
Is there any way I can make the program treat these characters correctly? What could be causing this problem?
Your solution to use the OEM code points is the right way to go, codepage 850/437 is the default code page for the console and therefore should work. You could also use SetConsoleOutputCP to ensure the correct code page is used for the console.
Having said that, what is happening when you do not use your workaround is that the source file is being saved using a different codepage ie. not codepage 850/437. The in memory representation of the source code is Unicode (probably UTF-8), when you save the file the in memory representation of the characters are mapped to the target code page for the file.
What you can do is to save the file using the 850/437 codepage as the target, I don't know how you do this in Qt Creator (If you can at all), in Visual Studio for example you can select the down arrow on the Save button and select "Save with encoding", you can then proceed to select the target codepage, in your case code page 850. This will ensure that the in memory code points are mapped correctly to the file to be compiled.
I hope that helps explain the issue.
It shouldn't be necessary to print the characters one at a time. Instead, you can use an escape sequence:
printf("\xDA\xBF\xC0\xD9\xB3\xC4\xFF");
Related
Well, I certainly should go to python since I did several functions of this type, keyboard event and mouse event, but decide to try to learn the windows api.
My goal is to know when button 1 of the mouse is pressed.
I created this file in a very beginner way, it returns in mouseData only 0.
The curious thing is that whenever I run it, it flashes my monitor at short intervals in blinks, but between 1 second with it off. Very strange that, execution is not viable.
Could someone help me understand and try to execute to see if it is only here.
Code:
int main()
{
DWORD mouseData = 0;
MOUSEINPUT tagMouse;
tagMouse.dx = 0;
tagMouse.dy = 0;
tagMouse.mouseData = mouseData;
tagMouse.dwFlags = MOUSEEVENTF_XDOWN;
tagMouse.dwExtraInfo = 0;
INPUT tagInput;
tagInput.type = INPUT_MOUSE;
tagInput.mi = tagMouse;
while (true) {
if (GetAsyncKeyState(VK_DELETE)) break;
SendInput(1, &tagInput, sizeof(INPUT));
printf("KEYWORD: %d\n", mouseData);
Sleep(500);
}
system("pause");
return 0;
}
I can reproduce your reported 'symptoms' - and the effect is really brutal!
Now, while I cannot offer a full explanation, I can offer a fix! You have an uninitialized field in your tagMouse structure (the time member, which is a time-stamp used by the system). Setting this to zero (which tells the system to generate its own time-stamp) fixes the problem. So, just add this line to your other initializer statements:
//...
tagMouse.dwExtraInfo = 0;
tagMouse.time = 0; // Adding this line fixes it!
//...
Note: I, too, would appreciate a fuller explanation; however, an uninitialized field, to me, smells like undefined behaviour! I have tried a variety of other values (i.e. not zero) for the time field but haven't yet found one that works.
The discussion here on devblogs may help. This quote seems relevant:
And who knows what sort of havoc that will create if a program checks
the timestamps and notices that they are either from the future or
have traveled back in time.
I'm trying to make a card game and I want to use the actual card suit symbols to print cards as so:
5♣ J♦ 10♠ Q♥
Problem is I literally have zero idea how to code these symbols to print successfully in a program.
You'll need to use the unicode characters for those symbols along with a font that supports them. This page lists the unicode character code for various suits. They are:
Spade = U+2660, Heart = U+2665, Diamond = U+2666, Heart = U+2663
This will give you black suits. There's also characters for white suits.
You'll also need to make sure you are using wchar_t to represent the characters, not char as it won't be wide enough. Also, make sure you use functions like wprintf to do your output.
With Windows console font set to "Lucida Console" the following works:
#include <stdio.h>
int main (void)
{
int i;
for(i=3; i<=6; i++)
printf("%c", i);
printf("\n");
return 0;
}
Program output:
♥♦♣♠
Similarly with "Consolas" font.
I'm converting some source from VC6 to VS2010. The code is written in C++/CLI and it is an MFC application. It includes a line:
BYTE mybyte;
sscanf(source, "%x", &mybyte);
Which is fine for VC6 (for more than 15 years) but causing problems in VS2010 so I created some test code.
void test_WORD_scanf()
{
char *source = "0xaa";
char *format = "%x";
int result = 0;
try
{
WORD pre = -1;
WORD target = -1;
WORD post = -1;
printf("Test (pre scan): stack: pre=%04x, target=%04x, post=%04x, sourse='%s', format='%s'\n", pre, target, post, source, format);
result = sscanf(source, format, &target);
printf("Test (post scan): stack: pre=%04x, target=%04x, post=%04x, sourse='%s', format='%s'\n", pre, target, post, source, format);
printf("result=%x", result);
// modification suggested by Werner Henze.
printf("&pre=%x sizeof(pre)=%x, &target=%x, sizeof(target)=%x, &post=%x, sizeof(post)=%d\n", &pre, sizeof(pre), &target, sizeof(target), &post, sizeof(post));
}
catch (...)
{
printf("Exception: Bad luck!\n");
}
}
Building this (in DEBUG mode) is no problem. Running it gives strange results that I cannot explain. First, I get the output from the two printf statemens as expected. Then a get a run time waring, which is the unexpected bit for me.
Test (pre scan): stack: pre=ffff, target=ffff, post=ffff, source='0xaa', format='%x'
Test (post scan): stack: pre=ffff, target=00aa, post=ffff, source='0xaa', format='%x'
result=1
Run-Time Check Failure #2 - Stack around the variable 'target' was corrupted.
Using the debugger I found out that the run time check failure is triggered on returning from the function. Does anybody know where the run time check failure comes from? I used Google but can't find any suggestion for this.
In the actual code it is not a WORD that is used in sscanf but a BYTE (and I have a BYTE version of the test function). This caused actual stack corruptions with the "%x" format (overwriting variable pre with 0) while using "%hx" (what I expect to be the correct format) is still causing some problems in overwriting the lower byte of variable prev.
Any suggestion is welcome.
Note: I edited the example code to include the return result from sscanf()
Kind regards,
Andre Steenveld.
sscanf with %x writes an int. If you provide the address of a BYTE or a WORD then you get a buffer overflow/stack overwrite. %hx will write a short int.
The solution is to have an int variable, let sscanf write to that and then set your WORD or BYTE variable to the read value.
int x;
sscanf("%x", "0xaa", x);
BYTE b = (BYTE)x;
BTW, for your test and the message
Run-Time Check Failure #2 - Stack around the variable 'target' was corrupted.
you should also print out the addresses of the variables and you'll probably see that the compiler added some padding/security check space between the variables pre/target/post.
I am making a project in C. Its simple, just a Hangman Game.
Got the logic already cause I've done that only in console.
Now, I'm trying to do it in C again with GRAPHICS. I am using Turbo C.
I've read some of the functions of graphics.h: so far I've seen outtext() / outtextxy() something like that. It can print a string.
Can you input a char or string in graphics? Searched a lot but seen nothing.
Seen only drawing shapes examples.
How do you input characters, integers etc. in the graphics mode?
From memory, while you can use regular stdio functions printf, scanf, and gets, the graphics driver will paint them over your screen onto a "virtual cursor" position and scroll the screen when it reaches the bottom. You can use the nonstandard conio.h functions such as gotoxy and attempt to position the cursor, but it's still a mediocre way of inputting text, messing up the graphics stuff. You also cannot use the fancy fonts!
So use getch to read characters without showing them; update a string buffer (manually handling special keys such as Backspace and Return), and draw that on the screen using a font of your choice.
A short sample snippet of code to get you started:
#define MAX_INPUT_LEN 80
char inputbuf[MAX_INPUT_LEN];
int input_pos = 0;
then, in your main loop
int the_end = 0;
do
{
outtextxy (0,0, inputbuf);
c = getch();
switch (c)
{
case 8: /* backspace */
if (input_pos)
{
input_pos--;
inputbuf[input_pos] = 0;
}
break;
case 13: /* return */
the_end = 1;
break;
case 27: /* Escape = Abort */
inputbuf[0] = 0;
the_end = 1;
break;
default:
if (input_pos < MAX_INPUT_LEN-1 && c >= ' ' && c <= '~')
{
inputbuf[input_pos] = c;
input_pos++;
inputbuf[input_pos] = 0;
}
}
} while (!the_end);
Before you draw the text, make sure to erase the previous line! I left that out because it's been too long ago I used Turbo-C.
For taking input from used.. you can use scanf function similar to how we take input in any non-graphics c program.
You can do this by using normal scanf function. And by using sprintf copy a integer/whatever variable into a string. Now you can use outtextxy to set the string in specified location using x,y axis. Check geeksforgeeks to learn sprintf syntax.
I know it is too late. Hope it helps someone else.!
Hello I am studying for a test for an intro to C programming class and yesterday I was trying to write this program to print out the even prime numbers between 2 and whatever number the user enters and I spent about 2 hours trying to write it properly and eventually I did it. I have 2 pictures I uploaded below. One of which displays the correct code and the correct output. The other shows one of my first attempts at the problem which didn't work correctly, I went back and made it as similar to the working code as I could without directly copying and pasting everything.
unfortunately new users aren't allowed to post pictures hopefully these links below will work.
This fails, it doesn't print all numbers in range with natural square root:
for (i = 2; i <= x; i++)
{
//non relevant line
a = sqrt(i);
aa = a * a;
if (aa == i);
printf("%d ",i);
}
source: http://i.imgur.com/WGG6n.jpg
While this succeeds, and prints even numbers with natural sqaure root
for (i = 2; i <= x; i++)
{
a = sqrt(i);
aa = a * a;
if (aa == i && ((i/2) *2) == i)
printf("%d ", i);
}
source: http://i.imgur.com/Kpvpq.jpg
Hopefully you can see and read the screen shots I have here. I know that the 'incorrect code' picture does not have the (i/2)*2 == i part but I figured that it would still print just the odd and even numbers, it also has the code to calculate "sqrd" but that shouldn't affect the output. Please correct me if I'm wrong on that last part though.
And Yes I am using Dev-C++ which I've read is kinda crappy of a program but I initally did this on code::blocks and it did the same thing...
Please I would very much appreciate any advice or suggestions as to what I did wrong 2 hours prior to actually getting the darn code to work for me.
Thank you,
Adam
your code in 'that' includes:
if (aa == i);
// ^
printf(...);
[note the ; at the end of the if condition]
Thus, if aa == i - an empty statement happens, and the print always occures, because it is out of the scope of the if statement.
To avoid this issue in the future, you might want to use explicit scoping1 [using {, } after control flow statements] - at least during your first steps of programming the language.
1: spartan programmers will probably hate this statement
Such errors are common. I use "step Over", "Step Into", "Break Points" and "watch window" to debug my program. Using these options, you can execute your program line by line and keep track of the variables used in each line. This way, u'll know which line is not getting executed in the desired way.