C++ newbie here with a quick question. How do I print the contents of CString to the Console?
Doing this
int main(array<System::String ^> ^args)
{
CString cs1 = _T("Hy");
CString cs2 = _T(" u");
CString cs3 = cs1 + cs2;
Console::WriteLine(cs3);
printf("%s", cs3);
return 0;
}
outputs "True" and "H" on the console. TIA.
I'm guessing you're compiling with Unicode turned on, but printf is an ANSI function, so it prints only the first character of the string. Use _tprintf to match your _T strings:
_tprintf(_T("%s"), cs3);
Console::WriteLine(gcnew System::String(cs3));
You need to cast your CString before printing
printf("%s ", (LPCTSTR)cs3);
This should work
Related
After printing, if I write the name I get:
Insert a name :Andrea
There is no space before Andrea, even if I put the space in the output. How can I add a space before writing the name?
#include <stdio.h>
int main() {
int string[8];
printf("\nInsert a name : ");
printf(" ");
scanf("%s", string);
printf("\nThe name is : %s", string);
return 0;
}
The code that you provided does not compile because the variable string is an array of integers (and not a string as you might think). And when you input the value of it, you're telling the compiler to expect a string ("%s" in scanf("%s", string")).
Change your string declaration to char string[8] and it should work (with the spacing you want):
Note that the value that goes into string will not contain more than 8 characters.
Actually, you did a small mistake in your code, you declared the string to be an array of int & from the code scanf("%s", string") the compiler expects from the user to enter a string as it contains %s as the format specifier. Hence, the code doesn't compile.
In order to correct this, you should declare string as char string[8] (string containing 8 characters).
The correct code is given below :
#include <stdio.h>
int main() {
char string[8];
printf("\nInsert a name : ");
scanf("%s", string);
printf("\nThe name is : %s", string);
return 0;
}
From the above correction your problem for space between input and output will be solved!
Here, is the output which is received from this correction :
I hope so this explanation will be helpful for you!
If any problem persists then feel free to ask in comments! ;-)
I'm just an amateur programmer...
And when reading, for the second time, and more than two years apart, kochan's "Programming in Objective-C", now the 6th ed., reaching the pointer chapter i tried to revive the old days when i started programming with C...
So, i tried to program a reverse C string function, using char pointers...
At the end i got the desired result, but... got also a very strange behavior, i cannot explain with my little programming experience...
First the code:
This is a .m file,
#import <Foundation/Foundation.h>
#import "*pathToFolder*/NSPrint.m"
int main(int argc, char const *argv[])
{
#autoreleasepool
{
char * reverseString(char * str);
char *ch;
if (argc < 2)
{
NSPrint(#"No word typed in the command line!");
return 1;
}
NSPrint(#"Reversing arguments:");
for (int i = 1; argv[i]; i++)
{
ch = reverseString(argv[i]);
printf("%s\n", ch);
//NSPrint(#"%s - %s", argv[i], ch);
}
}
return 0;
}
char * reverseString(char * str)
{
int size = 0;
for ( ; *(str + size) != '\0'; size++) ;
//printf("Size: %i\n", size);
char result[size + 1];
int i = 0;
for (size-- ; size >= 0; size--, i++)
{
result[i] = *(str + size);
//printf("%c, %c\n", result[i], *(str + size));
}
result[i] = '\0';
//printf("result location: %lu\n", result);
//printf("%s\n", result);
return result;
}
Second some notes:
This code is compiled in a MacBook Pro, with MAC OS X Maverick, with CLANG (clang -fobjc-arc $file_name -o $file_name_base)
That NSPrint is just a wrapper for printf to print a NSString constructed with stringWithFormat:arguments:
And third the strange behavior:
If I uncomment all those commented printf declarations, everything work just fine, i.e., all printf functions print what they have to print, including the last printf inside main function.
If I uncomment one, and just one, randomly chosen, of those comment printf functions, again everything work just fine, and I got the correct printf results, including the last printf inside main function.
If I leave all those commented printf functions as they are, I GOT ONLY BLANK LINES with the last printf inside main block, and one black line for each argument passed...
Worst, if I use that NSPrint function inside main, instead of the printf one, I get the desired result :!
Can anyone bring some light here please :)
You're returning a local array, that goes out of scope as the function exits. Dereferencing that memory causes undefined behavior.
You are returning a pointer to a local variable of the function that was called. When that function returns, the memory for the local variable becomes invalid, and the pointer returned is rubbish.
Could you please let me know how to convert CStringArray* to C++/CLI array. I am creating a wrapper dll which needs my data to be converted to unmanaged code. I am able to use basic data types like double * but not for CStringArray *.
Thank you.
Here is the solution
#include <msclr/marshal.h>
#include <msclr/marshal_cppstd.h>
#include <msclr/marshal_atl.h>
CStringArray * myData; //Assume data is already filled
array<String ^> unmanagedData = gcnew array<String ^) (m_nDataCount);
for (int j = 0; j < m_nDataCount; j++)
{
String ^ stepName = marshal_as<String ^> (myData->GetAt(j));
unmanagedData[j] = stepName;
}
Marshaling as is the solution. Thanks to #crashmstr for helping me to crack this
I have been using the md5 implementation found in this page:
http://www.zedwood.com/article/121/cpp-md5-function
As it is it works fine. There is however this function:
// return hex representation of digest as string
std::string MD5::hexdigest() const
{
if (!finalized)
return "";
char buf[33];
for (int i=0; i<16; i++)
sprintf(buf+i*2, "%02x", digest[i]);
buf[32]=0;
return std::string(buf);
}
If I change sprintf to the safe version (sprintf_s), then I get an Access Violation Error at runtime. The only thing I change is the sprintf line, like this:
sprintf_s(buf+i*2, 33, "%02x", digest[i]);
It compiles fine but then I get the error. Any idea why ?
Since you pass an offset into your buffer, you also need to reduce the size you pass to snprintf_s. That is:
snprintf_s(buf+i*2, 33-2*i, "%02x", digest[i]);
l used ANDROID NDK 。so l want to format something。just use sprintf，but l can not use it with
wchar_t. is there some helps for me？
You probably want swprintf and friends, assuming Android has it like Posix and Linux systems.
Glib (from GTK) has functions for unicode manipulation and for string utilities. I believe you should be able to make it work on Android.
In Android OS NDK versions before 5.0 ("Lollipop"), the sprintf() does not support the "%ls" (wchar_t pointer) format specifier. Thus, the following statement compiles but does not execute correctly under NDK (pre-5.0):
char buffer [1000];
wchar_t *wp = L"wide-char text";
sprintf (buffer, "My string is: %ls", wp);
The workaround is to convert the wchar_t string to UTF-8 (which is a char *) using any one of the Open Source wide-to-utf8 implementations (e.g. the UTF8-CPP project), passing its pointer to sprintf:
// WcharToUtf8: A cross-platform function I use for converting wchar_t string
// to UTF-8, based on the UTF8-CPP Open Source project
bool WcharToUtf8 (std::string &dest, const wchar_t *src, size_t srcSize)
{
bool ret = true;
dest.clear ();
size_t wideSize = sizeof (wchar_t);
if (wideSize == 2)
{
utf8::utf16to8 (src, src + srcSize, back_inserter (dest));
}
else if (wideSize == 4)
{
utf8::utf32to8 (src, src + srcSize, back_inserter (dest));
}
else
{
// sizeof (wchar_t) is not 2 or 4 (does it equal one?)! We didn't
// expect this and need to write code to handle the case.
ret = false;
}
return ret;
}
...
char buffer [1000];
wchar_t wp = L"wide-char text";
std::string utf8;
WcharToUtf8 (utf8, wp, wcslen (wp));
sprintf (buffer, "My string is: %s", utf8.c_str ());
Starting with Android 5.0 ("Lollipop"), sprintf() supports the "%ls" format specifier, so the original sprintf() code above works correctly.
If your Android NDK code needs to run on all version of Android, you should wrap all your wchar_t pointers passed to sprintf with a macro like the following:
#define CONVERTFORANDROID(e) (GetSupportsSprintfWideChar () ? (void *) e : (void *) WcharToUtf8(e).c_str ())
char buffer [1000];
wchar_t *wp = L"wide-char text";
sprintf (buffer, "My string is: %ls", CONVERTFORANDROID(wp));
The GetSupportsSprintfWideChar() function should be a local function that returns true if the running Android OS is 5.0 or above, while returning false if the OS is pre-5.0.