strcat, strcpy..........doesn't work

[[praetorian]]

I can't get strcat and strcpy to work.......see the code below:

char word[10] = "hello";
char word2[10] = "hi again";

char word3[2];

strcpy(word3, word[0])
strcat(word3, word2[0])

cout << word3;

should output: hh

I've checked the tutorial, but I can't get it to work anyway.......

any ideas?

thanks!

[kedaman]

that won't work, word[0] and word2[0] are char's not C strings.
you could do
word3[0]=word[0];
word3[1]=word2[0];

[[praetorian]]

Ok, thanks!

But I wanted to use strcat and strcpy.........and not what you suggested, but thanks anyway

[kedaman]

strcat and strcpy works only with C strings, if you want to go with C strings then you need a buffer two which you copy the substrings "h" from word and "h" from word2

[CornedBee]

I wonder why people want to use a more complicated approach...

[jim mcnamara]

char word[10] = "hello";
char word2[10] = "hi again";

char word3[21];
memset(word3,0x0,sizeof(word3));
strcpy(word3, word);
strcat(word3, word2);

cout << word3;

word3[0=word[0];
word3[1]=word2[0];
word3[2]=0x0;
cout<< word3 << endl;

[CornedBee]

Originally posted by jim mcnamara

word3[2]=0x0;

Yeah, this is important!

[[praetorian]]

problems with arrays and strcat........again!

char word[10] = "Pointer";
char word2[20] = "Procrastinate";

char word3[2];

word3[0] = word[0];
word3[1] = word2[0];
word3[2] = 'r';

char word4[10] = "problem";

strcat(word3, word4);

cout << word3;

Should output: PPrproblem, but doesn't do that.......any ideas? and why?

thanks again!

[jim mcnamara]

Yes. word3 only holds 2 characters.

[[praetorian]]

so, Should I change word3[2] to word3[3] and the problems will disappear?

I get a lot of strange characters between the two vectors when I use strcat..........???

[jim mcnamara]

char word3[21];

[jim mcnamara]

use
memset(word3,0x0,sizeof(word3));

C string depend on there being a null terminating character.
In other words for strcat, strcpy and strWHATEVER() to work, there must be an ASCII 0 character at the end of the string.
Start out by setting the whole string to ASCII 0 - what memset does above. It always works.

[kedaman]

Humm, i don't like this, if you want to stay with C strings then do so but don't mix in char's.

Jim, i think the functions will put the terminating null themself won't they?

[[praetorian]]

Jim:
Thanks, I think I get it now!

I think I've to read up a little on c-strings, I mix up everything all the time..........

Thanks for helping me and your patience!

[CornedBee]

Basically a char array must have at least as much space as is needed for all the characters you want to fill in + 1:

word3[0] = word[0];
word3[1] = word2[0];
word3[2] = 'r';
char word4[10] = "problem";

strcat(word3, word4);

You need at least char word3[11] for this.

Keda: strcat will add a '\0' at the end, but after this:
word3[0] = word[0];
word3[1] = word2[0];
word3[2] = 'r';
there is no '\0' at the end, therefore strcat does not know where to put the string.

[jim mcnamara]

Kedaman -

Some string functions don't play fair -- strncpy() for example. It does NOT put a terminating null character.

This is why calloc() exists - it stands for character allocation - it fills allocated memory with nulls.

[jim mcnamara]

(after reading CB's post)

Plus, strcpy() is the only function smart enough to place the source string correctly into the destination string when the destination string is full of garbage. strcat(), strncat(), etc must start at a terminating null. Using unitialized strings, then some string functions on top of it-- that is a great way to trash memory.

[[praetorian]]

Thanks for your help guys! It works! it works!

thanks for your patience

[kedaman]

Originally posted by jim mcnamara
Kedaman -

Some string functions don't play fair -- strncpy() for example. It does NOT put a terminating null character.

This is why calloc() exists - it stands for character allocation - it fills allocated memory with nulls.

What a disappointment how about

inline char* strncpy2(char* to,const char* from, int n){
    *(to+n+1)=0;
    return strncpy(to,from,n);
};