Assigning char * to CString Object :: C++

[kuphryn]

Hi.

I have a char * to a data buffer. What is the best way to assign data from char * into a CString object? For example:

-----
// char *myChar = new char[10];
// memcpy(myChar, "abcdefghij", 10);
// CString myString;
-----

What is the best say to insert data from myChar into myString?

Thanks,
Kuphryn

 

[singh]

Use the '=' operator.
myString = myChar;

 

[kuphryn]

Okay. Thanks.

Kuphryn

 

[Adrian Tung]

Just a note in your code: you should use strcpy or strncpy instead of memcpy for your code. Also remember that your strings are null-terminated, so you should always have one element more than the number of character in your string for the null character.

char *myChar = new char[11];
strcpy(myChar, "abcdefghij"); // -> your string is actually { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', '\0' }
CString myString = myChar;


atwl

 

[kuphryn]

Thanks.

I added a null terminator.

Why do you prefer strcpy over memcpy? From what I know, memcpy can handle both null-terminated string and raw data buffer.

Kuphryn

 

[Adrian Tung]

True, memcpy can handle them but you don't always know the length of your strings. In such situations, strcpy will be more efficient compared to a strlen+memcpy.


atwl

 

[kuphryn]

Nice! You're right. Thanks.

Kuphryn

 

[CodeJockey]

Based on your example code, you could also use the CString constructor:

Instead of

CString myString;

use

CString myString( myChar, 10 );

which will construct the CString and initialize it with the 10 characters from the myChar array.

 

[kuphryn]

Nice! Thanks.

For the second parameter, do I include the null-terminator too?

-----
// char *myChar = new char[11];
// strcpy(myChar, "abcdifghi");
// myChar[10] = '\0';
// CString myString(myChar, ???)
-----

??? = 10 or 11

Kuphryn

 

[CodeJockey]

That's up to you.

The CString itself will add a null terminator to it's internal copy of the string, after the specified number of characters have been copied.

Examples:

CString str3( "abc", 3 ); // str3 = {'a', 'b', 'c', '\0'}
CString str4( "abc", 4 ); // str4 = {'a', 'b', 'c', '\0', '\0'}

str3.GetLength() will return 3
str4.GetLength() will return 4

of course, easier still is to use

CString str( "abc" );

If you are trying to work with blocks of binary data that might contain values from 0x80 through 0xff, inclusive, or might contain embedded nulls (0x00), then you are probably better off using arrays of unsigned char, since the CString class is not designed to handle anything but null terminated character strings.

 

[kuphryn]

Okay. Thanks.

Kuphryn