Convert char array to CString in c++

Question

I am unable to convert the char * to CString.. the last 2 print lines print nothing...I need it as part of cstring to be able to pass it to a function..

char result[500];
strcpy(result, "\\\\.\\pipe\\");                    
strcat(result, a["BLOB"][i].GetString());// just appending to "result" a string I am reading from json file..
CString  temp(result);
printf("\n1-The pipeName we are looking at is %s \n", result);
printf("\n2-The pipeName we are looking at is %s \n", temp);
printf("\n3-The pipeName we are looking at is %s \n", CString(result,500));

What is CString and where does it come from? It's not part of standard C++. — Thomas
– Thomas, Commented Oct 14, 2020 at 18:15
Between CString and .GetString(), I am assuming this is referring to WinAPI, and have added the tag... a complete example (with includes) would have clarified that. — DevSolar
– DevSolar, Commented Oct 14, 2020 at 18:17
@DevSolar It is probably this, which is in mfc, rather than winapi. — Tanveer Badar
– Tanveer Badar, Commented Oct 14, 2020 at 18:19
@TanveerBadar: OK... I come from the Amiga and went from there directly to Linux, so everything from Microsoft is "WinAPI" to me. :-D Feel free to re-tag. — DevSolar
– DevSolar, Commented Oct 14, 2020 at 18:26
@ThomasMatthews: It's the MFC's (Thanks, Tanveer) C++ string type, and has been well before the monstrosity that is C++/CLI ever saw the light of day. — DevSolar
– DevSolar, Commented Oct 15, 2020 at 9:07

Tanveer Badar · Accepted Answer · 2020-10-14 18:15:26Z

2

How would printf() know what CString is? What a class is? How to convert CString to a c-style string?

This is working as expected.

What you are looking for is probably documented here, based on the assumption that MFC/WFC also provide a CString.

answered Oct 14, 2020 at 18:15

Tanveer Badar

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TheUndeadFish · Accepted Answer · 2020-10-14 18:17:39Z

2

printf is crude. Using %s with printf will assume that the first pointer-size amount of bytes in whatever you pass to it are actually a pointer to a string (aka char*).

That may or may not be true for CString. In your case it seems that it isn't.

To use printf you need to do it more like:

printf("\n2-The pipeName we are looking at is %s \n", temp.GetString());

Or else just stop using printf and use something with more type-safety, such as cout

answered Oct 14, 2020 at 18:17

TheUndeadFish

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dxiv · Accepted Answer · 2020-10-14 18:25:35Z

2

Build the string directly into the CString, and use the builtin cast to const char * when printing.

CString  temp("\\\\.\\pipe\\");
temp += a["BLOB"][i].GetString(); // or: temp.Format("\\\\.\\pipe\\%s", a["BLOB"][i].GetString());
printf("-The pipeName we are looking at is %s\n", (const char *)temp);

answered Oct 14, 2020 at 18:25

dxiv

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2 Comments

ccoding Over a year ago

The format arguments we are passing are incorrect.. any suggestions?

dxiv Over a year ago

@ccoding What's the exact line of code the error points to? Also, you don't say what type a["BLOB"][i].GetString() returns, but if it's not a const char * then you probably need to add a cast to that.

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