What is the meaning of _T("xyz")?

Question

I wanted to understand the use of _T("xyz") in the code below:

#include<CString.h>
int main()
{
   uint32_t xyz = 15;
   LPCSTR Desc = "xyz value is : ";
   CString Value;
   Value = (LPCSTR)Desc + _T("xyz");
}

Will the above code display:

xyz value is : 15

or

xyz value is : xyz

How to display -

xyz value is : 15

Read this: https://msdn.microsoft.com/en-us/library/dybsewaf.aspx. Using `_T` in this case it totally wrong. — Jabberwocky, Oct 17 '18 at 12:06
do you want to know what or why? for what, you just need to run the code, no? — 463035818_is_not_an_ai, Oct 17 '18 at 12:08
... and `Value = (LPCSTR)Desc + _T("xyz");` is totally wrong too. — Jabberwocky, Oct 17 '18 at 12:08
Don't use `CString.h`, it's an ancient non-portable hack from times when C++ didn't have a usable string class. — n. m. could be an AI, Oct 17 '18 at 12:10
I'm not sure the duplicate is helpful here. Voted for repopening — Jabberwocky, Oct 17 '18 at 12:24
whats wrong with `std::cout << "xyz value is " << xyz;` ? Do you **have** to use `CString.h` ? — 463035818_is_not_an_ai, Oct 17 '18 at 12:24
@Jabberwocky agree, maybe it was even a post like that that made OP think they need it for their case — 463035818_is_not_an_ai, Oct 17 '18 at 12:25

score 1 · Answer 1 · answered Oct 17 '18 at 12:11

1

The _T macro is used to simplify transporting code for international uses.

See https://msdn.microsoft.com/en-us/library/c426s321.aspx for more information.

answered Oct 17 '18 at 12:11

Neil Stoker

284
3
16

1

... at least that's what Microsoft would have developers believe. – Quentin Oct 17 '18 at 12:13

Jabberwocky · Accepted Answer · 2018-10-17T12:34:42.210

0

You probably want this:

uint32_t xyz = 15;
LPCWSTR Desc = L"xyz value is : %d";
CString Value;
Value.Format(Desc, xyz);

Forget about the _T macro. What makes you think you should use it?

Or maybe you need this:

uint32_t xyz = 15;                // integer variable containing the number 15
CString stxyz;                    // CString variable
stxyz.Format(L"%d", xyz);          // stxyz contains "15" now

LPCWSTR Desc = L"xyz value is : ";  // Desc points to the string literal "15"

CString Value = Desc + stxyz;     // Value contains concatenation of Desc and stxyz

edited Oct 17 '18 at 12:34

answered Oct 17 '18 at 12:15

Jabberwocky

48,281
17
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I have two string for which I need to concatenate – C A Anusha Oct 17 '18 at 12:17
@CAAnusha OK, so you need to transform `xyz` into string first. BTW `"XYZ"` is a string literal, its content is in no way related to the identifier `xyz`. – Jabberwocky Oct 17 '18 at 12:18
I thought that is used to convert any non-string value to string – C A Anusha Oct 17 '18 at 12:21
_I thought that is used to convert any non-string value to string_: absolutely not. You need to learn at least the basics of C++ to understand why my answers work. – Jabberwocky Oct 17 '18 at 12:22
I am using a user defined datatype basically a union instead of uint32_t .. How should I store in string then? – C A Anusha Oct 17 '18 at 12:30
I am getting below error Severity Code Description Project File Line Suppression State Error C2664 'void ATL::CStringT::Format(const wchar_t *,...)' : cannot convert parameter 1 from 'const char [3]' to 'const wchar_t *' – C A Anusha Oct 17 '18 at 12:31
Replace `LPCSTR` with `LPCWSTR` and replace `"xyz value is : "` with `L"xyz value is : "`. – Jabberwocky Oct 17 '18 at 12:34

What is the meaning of _T("xyz")?

2 Answers2