C help!

[leezard]

is the following the same???

void strcat(char s[], char t[])
{

int i,j;
i = 0;
while (s) i++;
j = 0;
while(t[j])
{
s = t[j];
j++;
i++;
}
s=0;
}

________________________________________________

void strcat ( char *sPtr , char *tPtr )
{

int i , j;
i = 0;
while ( *(sPtr + i) ) i++;
j = 0;
while ( *(tPtr + i) )
{
*(sPtr + i) = *(tPtr + i);
j++;
i++;
}
*(sPtr + i) = 0;
}

 

[manly]

They look very similar.

But I think the usage of s in the array-based implementation has a bug. Notice you never index into the array, as is done with t.

This duality of arrays and pointers is covered very specifically in K&R. You should check that book to see exactly how it should be done.

 

[Descartes]

I wrote a huge post then realized his formatting was hosed, so the issues I noted weren't really issues.

Bah...

 

[ElDonAntonio]

yeah the [ i ] are converted to italics. I suggest switching to "k" instead of "i" in your code.

 

[m0ti]

nope, they're not the same. in the first one you should almost definitely have *s = t[j], and then s++ (what you have shouldn't work. you don't copy any characters, and you don't move s). also at the end you should do *s = 0, and not s=0 (s is a pointer effectively!).

Actually, now that I think about it, I'm not sure if you even are allowed to move where s points to, since you received the parameter as an array.

 

[stndn]

Originally posted by: leezard (and modified by stndn)
is the following the same???

void strcat(char s[], char t[])
{

int k,j;
k = 0;
while (s[k]) k++;
j = 0;
while(t[j])
{
s[k] = t[j];
j++;
k++;
}
s[k]=0;
}

________________________________________________

void strcat ( char *sPtr , char *tPtr )
{

int k, j;
k= 0;
while ( *(sPtr + k) ) k++;
j = 0;
while ( *(tPtr + k) )
{
*(sPtr + k) = *(tPtr + k);
j++;
k++;
}
*(sPtr + k) = 0;
}

---- yup, i have too much time on my hand ....
but not too much to make me think of the problem ...


-1066-

 

[Chooco]

what does
void strcat ( char *sPtr , char *tPtr )
even mean? i mean those char *sPtr , char *tPtr
i've seen similar examples in my C++ manuals such as this at the top:
int main(int arg, char* pszArgs[])

what does that mean exactly? the code i saw this from is a basic loop program demonstraighting the looping of -- and ++

 

[HigherGround]

m0ti you should've check Descartes' and ElDonAntonio's replies, oh and the functions posted are not the same ...

while ( *(tPtr + i) )
{
*(sPtr + i) = *(tPtr + i);
j++;
i++;
}

should been

while ( *(tPtr + j) )
{
*(sPtr + i) = *(tPtr + j);
j++;
i++;
}

and this is how I would've done it

void strcat(char* s, char* t)
{
int i=0, j=0;
for(;*(s+i); i++);
while(*(t+j))
*(s+i++) = *(t+j++);
*(s+i) = 0;
}

 

[singh]

Talk about unintelligible code. But, alas, I have seen much worse...

 

[HigherGround]

hmmm, I guess you could also do something like this

void strcat(char* s, char* t)
{
int i=0, j=0;
for(;*(s+i); i++);
do *(s+i++) = *(t+j++); while(*(t+j));
}

 

[leezard]

thanks guys/gals..........