c++ code -- error

[Ciur Eugen]

HI !

Could somebody help me in finding error in the following code ?
int ** t; // a table of pointers to int, t[i], is a pointer to int
int i;

t = new int*[10]; // memory allocation
for( i=0 ; i < 10; i++ )
{
t[i] = new int(); // memory allocation
}
for( i=0 ; i < 10; i++ )
{
printf("%d\n",t[i]); // shows some random data. Its ok !
}

for( i=0 ; i < 10; i++ ) // as far as I know *t[i] - is data to what
t[i] points
{ // so *t[i] = 202, copy that number in t[i] location
*t[i] = 202 ; // so now,*t[i] contains number 202
}
for( i=0 ; i < 10; i++ )
{
printf("%d\n",t[i]); // what ?? AGAIN GARBAGE!!! WHERE IS NUMBER 202
??
}

for( i=0 ; i < 10; i++ )
{
delete t[i] ; // free memory up
}

delete t; // free memory up

[Diomidis Spinellis]

Ciur Eugen wrote:

Could somebody help me in finding error in the following code ?
int ** t; // a table of pointers to int, t[i], is a pointer to int
int i;

t = new int*[10]; // memory allocation
for( i=0 ; i < 10; i++ )
{
t[i] = new int(); // memory allocation
}

Although your code is C++, the style is very close to C (you just
replaced malloc with new). You're not benefitting from the modern C++
facilities, and getting confused with pointers and memory handling.
Unless this is an academic exercise, I suggest you look into the
standard template library (STL) and specifically the vector container.

--
Diomidis Spinellis
Code Quality: The Open Source Perspective (Addison-Wesley 2006)
http://www.spinellis.gr/codequality?clcpp

[Phlip]

Ciur Eugen wrote:

Could somebody help me in finding error in the following code ?
int ** t; // a table of pointers to int, t[i], is a pointer to int
int i;

t = new int*[10]; // memory allocation
for( i=0 ; i < 10; i++ )
{
t[i] = new int(); // memory allocation
}
for( i=0 ; i < 10; i++ )
{
printf("%d\n",t[i]); // shows some random data. Its ok !
}
Don't use printf. It has thrown away the type of t[i], and is treating a
pointer as an integer. On some platforms, where pointers cannot easily
represent as integers, this could cause undefined behavior.

Read /Accelerated C++/, and don't use new, either. Use a std::vector<>, to
take care of these low level details.
for( i=0 ; i < 10; i++ )
{
printf("%d\n",t[i]); // what ?? AGAIN GARBAGE!!! WHERE IS NUMBER 202
??
}

It's at printf("%d\n", *t[i]);

You were printing the address again.

--
Phlip
http://c2.com/cgi/wiki?ZeekLand <-- NOT a blog!!!

[Chris Hills]

What is it supposed to do
what is it actually doing?
Is it homework?
In article <11**********************@t31g2000cwb.googlegroups .com>, Ciur
Eugen <ci********@gmail.com> writes

HI !

Could somebody help me in finding error in the following code ?
int ** t; // a table of pointers to int, t[i], is a pointer to int
int i;

t = new int*[10]; // memory allocation
for( i=0 ; i < 10; i++ )
{
t[i] = new int(); // memory allocation
}
for( i=0 ; i < 10; i++ )
{
printf("%d\n",t[i]); // shows some random data. Its ok !
}

for( i=0 ; i < 10; i++ ) // as far as I know *t[i] - is data to what
t[i] points
{ // so *t[i] = 202, copy that number in
t[i] location
*t[i] = 202 ; // so now,*t[i] contains number 202
}
for( i=0 ; i < 10; i++ )
{
printf("%d\n",t[i]); // what ?? AGAIN GARBAGE!!! WHERE IS NUMBER
202
??
}

for( i=0 ; i < 10; i++ )
{
delete t[i] ; // free memory up
}

delete t; // free memory up

--
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
\/\/\/\/\ Chris Hills Staffs England /\/\/\/\/
/\/\/ ch***@phaedsys.org www.phaedsys.org \/\/\
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

[Phlip]

Chris Hills wrote:

What is it supposed to do
what is it actually doing?
Is it homework?

While it's not the greatest post ever, I think its comments covered your
first two questions. And its homework status is irrelevant if it's a
well-formed post.

--
Phlip
http://c2.com/cgi/wiki?ZeekLand <-- NOT a blog!!!

[BigBrian]

Ciur Eugen wrote:

HI !

Could somebody help me in finding error in the following code ?
int ** t; // a table of pointers to int, t[i], is a pointer to int
int i;

t = new int*[10]; // memory allocation
for( i=0 ; i < 10; i++ )
{
t[i] = new int(); // memory allocation
}
for( i=0 ; i < 10; i++ )
{
printf("%d\n",t[i]); // shows some random data. Its ok !
}

for( i=0 ; i < 10; i++ ) // as far as I know *t[i] - is data to what
t[i] points
{ // so *t[i] = 202, copy that number in t[i] location
*t[i] = 202 ; // so now,*t[i] contains number 202
}
for( i=0 ; i < 10; i++ )
{
printf("%d\n",t[i]); // what ?? AGAIN GARBAGE!!! WHERE IS NUMBER 202
??
}

for( i=0 ; i < 10; i++ )
{
delete t[i] ; // free memory up
}

delete t; // free memory up

Look at your own comments! You day that *t[i] contains the number 202,
but you're printing t[i] which points to where the 202 is stored.

[Jim Langston]

"Ciur Eugen" <ci********@gmail.com> wrote in message
news:11**********************@t31g2000cwb.googlegr oups.com...

HI !

Could somebody help me in finding error in the following code ?
int ** t; // a table of pointers to int, t[i], is a pointer to int
int i;

t = new int*[10]; // memory allocation
for( i=0 ; i < 10; i++ )
{
t[i] = new int(); // memory allocation
}
for( i=0 ; i < 10; i++ )
{
printf("%d\n",t[i]); // shows some random data. Its ok !
This is actually not random data, it is the pointers expressed as integers.
}

for( i=0 ; i < 10; i++ ) // as far as I know *t[i] - is data to what
t[i] points
{ // so *t[i] = 202, copy that number in t[i] location
*t[i] = 202 ; // so now,*t[i] contains number 202
Right, the contents of the pointer t[i] now contains the value 202.
}
for( i=0 ; i < 10; i++ )
{
printf("%d\n",t[i]); // what ?? AGAIN GARBAGE!!! WHERE IS NUMBER 202
t[i] is the pointer, remember? If you want to see the value you have to
look at the contents. simply change t[i] to *t[i]
??
}

for( i=0 ; i < 10; i++ )
{
delete t[i] ; // free memory up
}

delete t; // free memory up

[Ciur Eugen]

Solved.