Copy characters from char array to char array

Question

I have a char array with the size of 128. I want to copy the first 32 to another char array. This is how i'm trying to do it:

char ticket[128];
data.readBytes(ticketLength, (BYTE*)ticket);
char sessionID[32];
strcpy(sessionID, ticket);

int userID = bdAuthService::checkLogin(sessionID);

The contents of "ticket" are "11aa14462ac96a9b389686672b99fa9e1IvtooKO6eVxVHO6URIQld8jFaceTaker" and when i'm trying to pass the sessionID to the checkLogin function it gets the same contents as ticket "11aa14462ac96a9b389686672b99fa9e1IvtooKO6eVxVHO6URIQld8jFaceTaker".

Can anyone help me here?

Looks like a bad mixture of zero terminated and non zero terminated strings — user2249683
– user2249683, Commented Nov 4, 2015 at 18:42

Vlad from Moscow · Accepted Answer · 2015-11-04 18:50:48Z

4

Use memcpy function instead.

memcpy( sessionID, ticket, sizeof( sessionID )  );

Take into account that sessionID won;t contain a string. It will contain "raw" characters.

As for function strcpy then it is designed to copy strings that is a sequence of characters termintaed by zero. So in case of your code fragment it will copy as many characters as there are characters in ticket before the character with value '\0' provided that such a character is present in ticket .

edited Nov 4, 2015 at 18:50

answered Nov 4, 2015 at 18:41

Vlad from Moscow

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7 Comments

Bill Adonopoulos Over a year ago

When i use memcpy like you said the sid inside the called functions gets the value "593378e02614ebf8468cb67ca319bedaðúÙ,ûÙ@ wÞUVSþÿÿÿ„úÙ<" So it gets the bytes i want but adding useless stuff..

gmoniava Over a year ago

@BillAdonopoulos: because it is not null terminated

Vlad from Moscow Over a year ago

@BillAdonopoulos What is useless stuff? You said that you need to copy 32 characters. So where are the useless stuff from?

Bill Adonopoulos Over a year ago

So how can i make it null terminated? If i set sessionID[33] i get null terminated string but it gets 33 characters not 32 that i need and with [32] it's not null terminated

Vlad from Moscow Over a year ago

@BillAdonopoulos I think that the problem is not with this copy operation. The problem is how ypu are using the result string further in your code.

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Anon Mail · Accepted Answer · 2015-11-04 18:41:08Z

0

You can use strncpy which allows you to specify the number of bytes to copy.

answered Nov 4, 2015 at 18:41

Anon Mail

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