Here is my simple code :
#include <stdio.h>
int main(){
printf("Hello new world\n");
char c[10];
scanf("%s",c);
printf("%s",c);
return 0;
}
Normal, We will see: Hello new world, after that, we input some string, and C will print this string for us.
But in my eclipse CDT, when running, console is empty. I must input a string first, for example, stackoverflow. after that, my program will print :
Hello new world
stackoverflow
I don't know why happen, please teach me to fix this.
Thanks :)
It's something that developers of Eclipse do not consider for a bug.
You can read more about this "bug" here:
https://bugs.eclipse.org/bugs/show_bug.cgi?id=173732
Anyway... Ugly but working solution is to put
fflush(stdout);
after every printf() and puts().
Related
I have a big issue. I develop in eclipse ide environment, mostly on windows but also on linux. This seems to be a general issue.
Before I save my project on eclipse I have certain spaces between functions or in the code somewhere. I don't want to reformat the code that is in place.
However, every single time I try to save my project. Those spaces disappear, and I cannot find the place where I should change this auto-formatting in my eclipse properties.
Please see example bellow:
First of all I don't touch the code but I receive it as bellow and have to make modifications elsewhere. So at the initial state of my file I have somewhere in the code two functions [functionOne, functionTwo]. Those two functions are separated by a new line [NL] and 6 spaces. The problem appears when I save my project and as you can see the two functions are not separated anymore by the same number of spaces.
Before saving my project:
public void functionOne(){
int i = 0;
while(i<150)
{
//blabla...
}
}
NL:123456
public void functionTwo(){
int i = 0;
while(i<150)
{
//blabla...
}
}
After saving my project:
public void functionOne(){
int i = 0;
while(i<150)
{
//blabla...
}
}
NL:1
public void functionTwo(){
int i = 0;
while(i<150)
{
//blabla...
}
}
I'm starting to be sick of this issue and really need help to solve this.
Not forgetting to mention that absolutely no "Save actions" is enabled!
I don't see anything on my format options neither, but I could be wrong.
Could someone please help me to find a solutions to this problem?
Best regards,
Greg
So that wasn't the "Save actions" but some plugin that I was using. Didn't had the time to check which one it is I just uninstalled the rarely/unused once. And for the moment it seems to work. I'll check later if the problem remains/reappears.
Thanks for your help.
Best regards,
Gregory
Hi i want to pass a data from my char device driver to serial port ttyS0..
I have created a simple char driver module which reads and write and it's my first tym doing it.. i am using debian guest os...
e.g.
echo "hello" > /dev/mydev
now when /dev/mydev receives the data it will then alter the string into something like "hello too" which is passed to my serial port /dev/ttyS0..
how can i alter the string?.. is it possible to use if statement inside mydev?
e.g
if(string=="hello"){
alterstringTO: hello to;
pass "hello to" /dev/ttyS0;
like echoing in terminal..
echo "hello to" > /dev/ttyS0
}
Is that possible?... or is there any other way doing it?
Here some of the code..
ssize_t dev_read(struct file *filp, char *buf, size_t clen, loff_t *f_pos){
short cnt =0;
while(clen && (msg[Pos]!=0))
{
put_user(msg[Pos],buf++);
cnt++;
clen--;
Pos++;
}
return cnt;
}
ssize_t dev_write(struct file *filp, const char *buf, size_t clen, loff_t *f_pos){
short dec = clen-1;
short cnt=0;
memset(msg,0,50);
Pos=0;
while(clen>0)
{
msg[cnt++] = buf[dec--];
clen--;
}
return cnt;
}
Thanks in advance..
Just a comment on writing to the serial port:
Remember the Linux foundations, everything is a file in Linux. To write to the device driver from a program you need to open the file for writing and then you can fprintf whatever data you want. You can do that from user space as well (the recommended way)
Refer to the following man pages:
man fopen
man fread/fwrite
man fprintf
man fclose
I'm not exactly sure what you are trying to achieve here, as the question and the intent seems unclear to me. I'll provide some guidance, but recommend that you edit your question and make it more readable.
Your snippet to compare strings is not correct. You can learn more about how to compare strings in C in here.
Altering a string in C is a basic operation that you learn when you start working with strings. This should help you getting started.
As final remark, please note that programming for the kernel requires extra care. A small mistake may lead to a crash and loss of data. If you really must, then the book Linux Device Drivers 3rd Edition is freely available and can help you further.
I am currently in a project involving data visualization of a signal captured from a device which has a Visual C++ API. I currently can log each datasample to file, but I'd like to do some sort of plot to screen.
I have had a previous successful experience with a similar job using socket between C++ and Python, but the code was lost. I have the Python socket "receiver" to reuse, but don't have the Visual C++ "sender" to reverse engineer or otherwise copy/paste.
My current Python code, which was working very fine, is:
import SocketServer
class SocketHandler(SocketServer.BaseRequestHandler):
def handle(self):
data = self.request[0].strip()
## do something with 'data' here!
server = SocketServer.UDPServer(("192.168.1.23", 8888), SocketHandler)
server.serve_forever()
And the part of the Visual C++ that currently logs to file and I want to send to the socket is:
#include <fstream>
//(...lots of code...)
short int * dataBuff;
unsigned int dataNum;
int isAcqRunning;
int startFromTrg, stopFromTrg;
unsigned int firstSample, lastSample;
int errcode;
int i;
std::ofstream out("./out.txt");
// device->transferData is called inside a loop
// to get data from aquisition hardware's buffer
errcode = device->transferData(&dataBuff, &dataNum, &isAcqRunning,
&startFromTrg, &stopFromTrg,
&firstSample, &lastSample);
if(errcode == 0)
{
printf("\n Acquired samples: %d", dataNum);
for (i=firstSample; i<lastSample; i++)
out<<dataBuff[i]<<'\n'; /////// I'd like to send dataBuff[i] via socket!!
}
//(...lots of more code...)
Possibly useful additional information:
I'm using VisualStudio 2010 in Windows7;
This is the first time I touch C++ code in my life, I use Python almost exclusively;
I haven't have success trying to follow C++ examples from books and sites because, as it appears, C++ and VISUAL C++ are NOT the same thing and can behave very differently :o(
I thank very much for any help, and for reading this.
(EDIT: if there is a better way to do that without any additional complexity overhead for a noob, I would be glad to try. I like the socket stuff because it is language-transparent and solved a previous problem with very good speed)
I'm a beginner in Perl and I get this message when I execute my code:
Use of uninitialized value $triggerCheck in numeric gt (>) at
./advanced-daemon.pl line 101.
This is the only error/warning I get when executing my code. The code, itself, works without any problems but I'm wondering what's the problem in that variable?
To reproduce the problem you can use this code:
while(1==1)
{
my $triggerCheck = "10";
if($triggerCheck < 10)
{
print "This var is < 10";
}
$triggerCheck = 9;
sleep 1;
}
Edit: I solved my problem. Sorry for bothering you all :)
There is absolutely nothing wrong with that code that you initially posted. Nor the code that you replaced it with (other than the annoying infinite loop).
It gets no errors or warnings and, when I change the initialisation to "9", it outputs the string.
In fact, given that your error message is complaining about > and there's no such symbol anywhere in your code, you have a serious mismatch between reality and your presentation of it.
Seriously, put together the minimal complete code sample that generates the error and post that. Helping people over the net is hard enough without being hobbled by fiction :-)
I'm getting a rather odd error message when attempting to wcout a wstring in vc++ 2008 express:
error C2679: binary '<<' : no operator found which takes a right-hand operand of type 'std::wstring' (or there is no acceptable conversion)
If I understand this correctly it's reporting that wcout does not accept a wstring? I ask someone to compile this code under linux and it runs fine. I also tried the same code on another computer with vc++ 2008 express and still fails. A known issue with std in vc++ 2008?
#include <iostream>
int main()
{
std::wstring unicode_test = L"Unicode var";
std::wcout << L"Unicode non-var" << std::endl;
std::wcout << unicode_test << std::endl; //<-- This line fails!
}
I'm using vc++ 2008 express sp1 with all the updates up to KB948127. I'm aware that console will need codepage changes but this isn't even compiling. Thanks.
You need to #include <string>. I'm not sure what the standard says, but I'm quite sure that <iostream> is not required to export all of <string>, if any.
[edit]At least cplusplus.com does not even list string as the types declared in <iostream>. No, it's not the standard, I know...[/edit]
For those with this problem, you may need to enable multi-byte printing in the console. See the answer here: https://stackoverflow.com/a/41584090/1599699
And my comment:
I was having trouble printing a wstring that I instantiated with a greater length than the data I was supplying due to sizeof(wchar_t) == sizeof(char) * 2, and then printing anything after that wasn't succeeding.