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It should not work at all. String constants declared as above are read-only, so you should not be able to use strcpy to overwrite one of them by another. When I try it I get an access violation on the write, as I would expect. I am not sure why your system does not give the fault, maybe a peculiarity of Arduino. But since strcpy is supposed to return the pointer to the destination field, Result will now point to the data that Source points to, i.e. "123", but the original data should be untouched.
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You cannot do that, it is a mistake. Your variables point to statically allocated (i.e. constant) strings you must NOT try to change.
The following program
#include <stdio.h>
#include <string.h>
int main()
{
char Result[] ="Result init ";
char Source[] = "123";
char Destination[] = "456";
strcpy(Destination, Source);
printf("%s %s\n", Destination, Source);
return 0;
}
on the other hand, outputs
123 123
Please note, parameter order in strcpy is important (like in any other C function, after all).
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Thanks, one of these days I'll hope to learn.
I did change the initialization and it did the trick with the exception of Result.
Can you explain to me why Result needs to be declared this way?
I appreciate all you guys time and I am sorry about the poor choice of variable names I did.
Thanks.
I am enclosing my full test code, just FYI , so do not pay much attention to it.
char *Result = {"0007890"};
char Destination[] = {"456"};
char Temp[] = {" "};
char Source[] = {"123"};
#ifdef DEBUG
lcd_i2c.clear();
//lcd_i2c.print("BuildAttribute...");
lcd_i2c.setCursor(0, 0);
lcd_i2c.print("Result ");
lcd_i2c.print(Result );
//for(;;);
lcd_i2c.setCursor(0, 1);
lcd_i2c.print("Source " );
lcd_i2c.print(Source );
//strcpy(PassedAttribute, "attribute");
lcd_i2c.setCursor(0, 2);
lcd_i2c.print("Dest " );
lcd_i2c.print(Destination );
lcd_i2c.setCursor(0, 3);
//lcd_i2c.print(Attribute);
//delay(2000);
//for(;;);
//return PassedAttribute;
#endif
//Result = strncpy(Source, "TESTDestination",2 );
printf("%s %s\n", Destination, Source);
Result = strcpy(Destination, Source);
printf("%s %s\n", Destination, Source);
//for (;;);
#ifdef DEBUG
lcd_i2c.clear();
//lcd_i2c.print("BuildAttribute...");
lcd_i2c.setCursor(0, 0);
lcd_i2c.print("Result ");
lcd_i2c.print(Result );
//for(;;);
lcd_i2c.setCursor(0, 1);
lcd_i2c.print("Source " );
lcd_i2c.print(Source );
//strcpy(PassedAttribute, "attribute");
lcd_i2c.setCursor(0, 2);
lcd_i2c.print("Dest " );
lcd_i2c.print(Destination );
lcd_i2c.setCursor(0, 3);
lcd_i2c.print("Temp ");
lcd_i2c.print(Temp);
//delay(2000);
for (;;);
//return PassedAttribute;
#endif
for(;;);
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Result must be declared as pointer to character (char *) because (as already explained by Richard) you are assigning it with strcpy return value. Please note such an assignment is useless since strcpy result is already in Destination array.
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Thanks.
I know the results are already known, but I was just using it to learn about the strcpy.
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This should exactly work:
#include <stdio.h>
#include <string.h>
int main(void)
{
char *Result = "Result init ";
char Source[256] = "123";
char Destination[256] = "456";
Result = strcpy(Source, Destination);
printf("Result = %s\nSource = %s\nDestination = %s\n", Result, Source, Destination);
return 0;
}
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Hi,
I have build a VC++ dll project that build fine in visual studio environment.
I need to deploy that project to a server, which does not have VS2012, so I wrote a batch file to execute the build tasks using
Msbuild.
Please look at the code below:
@ECHO OFF
for /f "tokens=2*" %%A in ('REG QUERY "HKLM\SOFTWARE\Microsoft\MSBuild\ToolsVersions\4.0" /v MSBuildToolsPath') DO (
set MSBuildToolsPathVS=%%B)
@ECHO "MSbuildexePath= " %MSBuildToolsPathVS%
set SolFilePath="C:\C++\DllCreateProj\DllCreateProj.vcxproj"
@ECHO "SolFilePath= "%SolFilePath%
cd %MSBuildToolsPathVS%
msbuild.exe %SolFilePath% /p:configuration=release;Platform=x64
The project build fine,except the following warning:
Quote: Creating "x64\release\DllCreateproj.unsucessfullbuild" because "alwayscreate" was specified
I had this message before for the same project at different location, so I copied solution, and rebuilt it, and there is no such message in VS IDE but msbuild gives this message
I modify the script to log the results as:
@ECHO OFF
for /f "tokens=2*" %%A in (
set MSBuildToolsPathVS=%%B)
@ECHO "MSbuildexePath= " %MSBuildToolsPathVS%
set SolFilePath="C:\C++\DllCreateProj\DllCreateSol.sln"
@ECHO "SolFilePath= "%SolFilePath%
set MSBuildLogPath="C:\C++\DllCreateProj\Buildlog.txt"
@ECHO "MSBuildLogPath= "%MSBuildLogPath%
cd %MSBuildToolsPathVS%
msbuild.exe %SolFilePath% /p:configuration=release;Platform=x64^
/fileLoggerParameters:LogFile=%MSBuildLogPath%;Verbosity=detailed;
/t:clean;rebuild
Now, the paths print out correctly and I have verified that.
However, "Buildlog.txt" is not created and also, after the "build Suceeded" message, I get following message twice
Quote: The filename,directory name ,or volume label syntax is incorrect.
So, I have following questions:
1) How do I solve the warning for "unsucessfulbuild" ?
2) How do I specify path for log file correctly.
3) Why do I get the "volume label incorrect " message, and is there a way to get more information about that?
4) Given path to msbuild that I have extracted, I need to modify "SolFilePath" and "msBuildLogPath" as being relative to ,say release path Quote: C:\C++\DllCreateProj\x64\Release
"
Any help with that?
Thanks
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Hi Guys!,
I'm getting a runtime error, and compiler is pointing at "free.c", shown below:
void __cdecl _free_base (void * pBlock)
{
int retval = 0;
if (pBlock == NULL)
return;
RTCCALLBACK(_RTC_Free_hook, (pBlock, 0));
retval = HeapFree(_crtheap, 0, pBlock);
if (retval == 0)
{
errno = _get_errno_from_oserr(GetLastError());
}
}
I couldn't troubleshoot where exactly is the issue..
It would be of great help if you can give some suggestions..
Thanks!
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int main(int argc, char* argv[])
{
<pre>
char fname[30];
char fpath[100]; char fpath1[100]; char fpath2[100];
memset(boolArray,0,sizeof(bool)*arraySize);
bool *pBool =boolArray + 10;
srand( (unsigned)time(NULL));
int rIndex2;
for(int i=0;i<10;++i){
memset(pBool,1,sizeof(bool)*12);
int rIndex = rand()%12;
pBool[rIndex]=0;
do{
rIndex2 = rand()%12;
pBool[rIndex2]=0;
} while (rIndex2==rIndex);
pBool +=12;
}
for (int j=0; j<NTRIALS;j++) printf("%d\t", boolArray[j]);
printf ("\n");
printf ("-----------------------------------\n");
printf ("-----------------------------------\n");
printf ("\n\n");
printf ("File name for logging:");
scanf("%s",fname);
printf ("\n\n");
printf ("[x] - Exit application\n");
printf ("\n\n");
resourceRoot = string(argv[0]).substr(0,string(argv[0]).find_last_of("/\\")+1);
sprintf(fpath,"%s\\%s%0d.dat",rootdir,fname);
pFile = fopen (fpath, "wb");
sprintf(fpath1,"%s\\%s%0d.pro",rootdir,fname);
pFile1 = fopen (fpath1, "w");
sprintf(fpath2,"%s\\%s%0d.arr",rootdir,fname);
pFile2 = fopen(fpath2,"w");
for (int j=0; j<NTRIALS;j++) fprintf(pFile2, "%d\t",boolArray[j]);
handler = new cHapticDeviceHandler();
numHapticDevices = handler->getNumDevices();
numHapticDevices = cMin(numHapticDevices, MAX_DEVICES);
int screenW = glutGet(GLUT_SCREEN_WIDTH);
int screenH = glutGet(GLUT_SCREEN_HEIGHT);
int windowPosX1 = 0;
int windowPosY1 = 0;
int windowPosX2 = WINDOW_SIZE_W;
int windowPosY2 = 0;
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
glutInitWindowSize (WINDOW_SIZE_W/2, WINDOW_SIZE_H/2);
mytimer.start(true); statetimer.start(true);
int i = 0;
while (i < numHapticDevices){
cGenericHapticDevice* newHapticDevice;
handler->getDevice(newHapticDevice, i);
printf("index number of device-> %d \n\n", i);
newHapticDevice->open();
newHapticDevice->initialize();
hapticDevices[i] = newHapticDevice;
cHapticDeviceInfo info = newHapticDevice->getSpecifications();
CreateWorld(world[i],camera[i],cursors[i],starts[i],targets[i],via[i],labels[i],scorelabels[i]
,forcevectors[i],poslabels[i], waitlabels[i]);
char str[30];
sprintf(str,"ROBOT %d",i);
window[i] = glutCreateWindow (str);
if (i==0) {
glutInitWindowPosition (windowPosX1, windowPosY1);
glutDisplayFunc(updateGraphics1);
}
else {
glutInitWindowPosition (windowPosX2, windowPosY2);
glutDisplayFunc(updateGraphics2);
}
glutReshapeFunc(reshape);
glutKeyboardFunc(keySelect);
i++;
}
via[0]->setPos(cVector3d( 0, 0.02, 0.03));
via[1]->setPos(cVector3d( 0, -0.02, -0.03));
simulationRunning = true;
cThread* hapticsThread = new cThread();
hapticsThread->set(updateHaptics, CHAI_THREAD_PRIORITY_HAPTICS);
cThread* loggingThread = new cThread();
loggingThread->set(updateLogging, CHAI_THREAD_PRIORITY_HAPTICS);
cThread* IOThread = new cThread();
IOThread->set(IOflush, CHAI_THREAD_PRIORITY_GRAPHICS);
glutMainLoop();
mytimer.stop();
statetimer.stop();
fclose(pFile);
fclose(pFile1);
fclose(pFile2);
close();
return (0);
}
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Why not remove everything that is not related to the problem, as it is just noise. Then we can look at what's left and make suggestions.
"One man's wage rise is another man's price increase." - Harold Wilson
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles
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This sort of error is caused by code overwriting the beginning (or end) of a heap block, and corrupting the heap control structures. One way to find such a problem is to wrap each of your blocks in a "signature" (see below), and periodically check that the "signature" is valid.
Original structure:
class foo
{
int baz;
char bar;
};
New structure:
class foo
{
long sig1;
int baz;
char bar;
long sig2;
};
Note that you can use the constructor to initialize the signature, and the destructor to check whether the signatures have changed. Your methods can check the validity of the signatures before performing any operations. You can also modify the signatures in the destructor, in order to catch accesses to freed memory.
A library of this sort is a basic tool for any C++ programmer. If you don't have such a library in your toolbox - write one!
If you have an important point to make, don't try to be subtle or clever. Use a pile driver. Hit the point once. Then come back and hit it again. Then hit it a third time - a tremendous whack.
--Winston Churchill
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This is usually sourced by writing to an array with an out of bound index.
So you must check all your allocated arrays (which may include arrays that are allocated by library functions). Starting with your own ones, search for any call to new as array; e.g.:
type arrayName = new type[size];
Then for each array check the accesses for invalid indexes (index < 0 or >= size). You can do this manually by reading your source or by guarding all accesses with assertions in debug builds:
assert(index > 0 && index < arrayNameSize);
arrayName[index] = someValue;
Your posted code does not contain the allocation of most. So it can't be checked by us. But there are many candidates: boolArray and all arrays used inside the 'while (i < numHapticDevices)' loop (e.g. hapticDevices).
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This seems very silly and basic -
The function description is pretty clear
Convert an unsigned long integer into a string, using a given base
So why I keep printing numbers and NOT ASCII letter?
I need a pointer to string - not numeric value.
And I am sorry to ask such stupid question.
Cheers
Vaclav
<pre>
int base = 10;
long value = 73;
char buffer[33];
unsigned long RANDOM = random(65, 79);
for( base = 2; base <= 16; base = base + 2 ) {
printf( "%2d %s\n", base,
ultoa( RANDOM, buffer, base ) );
}</pre>
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I suppose, you know that
printf("%d\n", ul);
and
printf("%s\n", ultoa(ul, buffer, 10));
should produce the same output.
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Vaclav_Sal wrote: So why I keep printing numbers
Because that is what ultoa creates. It takes a numeric value (long) and converts it to printable characters. Try an input value of 127 instead of RANDOM.
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So itoa is really NOT "integer to ASCII" conversion, right?
I knew it was a silly question.
I suppose I can use some kind of lookup method the get from random index # to character array of alphabet.
I'll check stdio.
Thanks
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Vaclav_Sal wrote: So itoa is really NOT "integer to ASCII" conversion, right?
Yes, of course it is. It converts a binary integer to a set of printable (ASCII) characters. What else would you expect it to do?
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If all you need is the ASCII character corresponding to the given integer than a cast is enough, e.g.
printf("%c\n", (char) RANDOM);
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Hello,
I have access to array of pixel data (size:512x512x8bpp) from a framegrabber which I currently assign to a 8bpp bitmap which is assigned to a GDI+ graphics object later on.
Now, I would like to convert my array of 8bpp pixel data into 24bpp (BGRA, but I have no use for Alpha channel) and assign it to my bitmap and then modify individual pixel data to different colors depending on other conditions.
When I say efficient, I want it to be done in real-time without much delay.
Any suggestions?
thanks
PKNT
modified 31-Jul-15 14:46pm.
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Did you try the straightforward way (that is filling the ARGB memory area in a loop) and measured its performance?
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When the input data are 8 bit gray scale values just assign them to the R, G, and B values and set the aplha value to zero:
RGBA *out = new RGBA[512 * 512];
for (unsigned i = 0; i < 512 * 512; i++)
{
out[i] = (in[i] << 16) + (in[i] << 8) + in[i];
}
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Although I use C# most of the time, I try to use C for small exercises -- to keep my C sharp! 
Anyway... I don't recall having to pass arrays back when I was using C full-time (in the 90s), so I don't know which technique is preferred.
As I see it, there are two basic techniques as precedents in C:
0) Passing the length of the array with the array -- e.g. main ( int argc , char *argv[] )
1) Having a "special value" at the end of the array to indicate the end -- e.g. NULL-terminated strings.
So, if I want to pass an array of structs (four ints), which technique is preferred by the C/C++ community?
I'm actually considering door number...
2) Using a linked list instead. It just seems cleaner, though memory usage is actually increased by 25% in this case.
Again, this is just an exercise, but practicing poor technique can be worse than not practicing at all.
So, what say you? If you have to pick door 0 or door 1, which do you prefer?
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Which method you use depends on what your data looks like. If you have an array of int, then there may not be a special value that can be the sentinel for the end of the array. On the other hand if you have an array of pointers to something, then maybe a NULL pointer is a good choice as a sentinel. Not always, though. If you had an sparse array of pointers, it would be conventional for the empty elements to be NULL, so you could not use that as the sentinel.
Advantages to passing the length are that you can work your way forwards or backwards through the array without having to count how many first, and you know the bounds, so you shouldn't have any Undefined Behaviour from trying to access outside the array.
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Thanks.
With these particular structs, there is a field in which a 0 (or anything less than 1) could easily be used to indicate that the item is the terminator.
And in this particular exercise, I need to visit each item once per call, so knowing the length would only keep me from going off the end, not aid in navigation.
I'll give door 1 a try. I think that will require only that I allocate one more item and make a small change to the for loop I would otherwise use.
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Unfortunately in C language there has not any concept of bounds checking.If we are inserting an array elements which exceeds size of an array automatically it is treated as garbage value.
Example:
#include<stdio.h>
#include<conio.h>
main()
{
int a[10];
a[3]=4;
a[11]=3;//does not give segmentation fault
a[25]=4;//does not give segmentation fault
a[20000]=3; //gives segmentation fault
getch();
}
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