Null terminating a character pointer?

Hello, I have a void pointer 'data' which I used to cast to a string later on by a method that sends in another data

Im using

Code:

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strncpy((char*)this->data,data,len);

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How do I make sure that this->((char*)data) is null terminated?

Code:

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if(data[strlen(data)] == '\0')
                cout<<"yes"<<endl;

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edit: Nope, won't work. strlen() only works on null terminated strings.

What I meant was, how do I null terminate it?

strcpy((char*)data,'\0'); ?

Isnt that deprecated?

strcpy() only works with null terminated strings, too--that's how strcpy finds the end of the first string.

I don't think you can unless you know the size of the array. With any C++ array, you have to pass the size around with it--otherwise you'll go out of bounds.

So what do I do when my assignment says

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IOLabel &operator=(const char *data); copies the maximum of "len" character from the incoming argument "data" into the data attribute of the class. Make sure that the data is null terminated.

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strncpy's destination string will be 0-terminated as long as the source-string is shorter then the specified nr of characters.
To be shure that it is alwais 0-terminated you could just

Code:

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((char*)this->data)[len-1]='\0';

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Kurt

It's ambiguous, but this sentence:

Quote:

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Make sure that the data is null terminated.

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is probably referring to the data member of the class. Typically, you'll use 'new' to create the memory for your member variable to store len + 1 characters. Then you copy each character from the source string into your member variable string, and finally for the last index position of your member variable string, you assign it a '\0' character.

Quote:

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Originally Posted by INFERNO2K

strcpy((char*)data,'\0'); ?

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Aside from the syntax error (strcpy expects two pointers to characters, not a pointer and a char) this will cause the first character of data to be the null character, thus emptying the string. The syntax error can be fixed by doing:

Code:

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strcpy((char*)data, "");

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Quote:

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Originally Posted by 7stud

strcpy() only works with null terminated strings, too--that's how strcpy finds the end of the first string.

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It only matters that the source is null terminated. You are probably thinking of strcat() which appends the source onto the destination.