Stroustrup 5.9, exercise 11

[arnuld]

there is no "compile-time error". after i enter input and hit ENTER i
get a run-time error. here is the code:

---------- PROGRAMME --------------
/* Stroustrup, 5.9, exercise
11

STATEMENT:
Read a sequence of words from the input. use "quit" as the
word
to terminate the input. Print the words in the order they
were
entered. don't print a word twice.modify the programme to sort
the
words before printing
them.

*/
#include<iostre am>
#include<string >

int main()
{
const std::string EOI = "quit"; // End Of
Input
char* user_input = "";

const int max_input = 1000;
char* collect_input[max_input + 1];

for(int i=0; user_input != EOI || i < max_input; ++i)
{
std::cin >user_input;
collect_input[i] = user_input;
}

return 0;
}

------------- OUTPUT -------------
[arch@voodo tc++pl]$ g++ 5.9_ex-11.cpp
[arch@voodo tc++pl]$ ./a.out
like
Segmentation fault
[arch@voodo tc++pl]$

[Victor Bazarov]

arnuld wrote:

there is no "compile-time error". after i enter input and hit ENTER i
get a run-time error. here is the code:

---------- PROGRAMME --------------
/* Stroustrup, 5.9, exercise
11

STATEMENT:
Read a sequence of words from the input. use "quit" as the
word
to terminate the input. Print the words in the order they
were
entered. don't print a word twice.modify the programme to sort
the
words before printing
them.

*/
#include<iostre am>
#include<string >

int main()
{
const std::string EOI = "quit"; // End Of
Input
char* user_input = "";

WHY? Why 'char*'? Why couldn't this also be 'std::string'?

[..]

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

[arnuld]

On Apr 2, 8:43 pm, "Victor Bazarov" <v.Abaza...@com Acast.netwrote:

WHY? Why 'char*'? Why couldn't this also be 'std::string'?

BECAUSE...Becau se ... ;-)

i have not across "std::strin g" yet. presently at Stroustrup chpater 5.

[Victor Bazarov]

arnuld wrote:

>On Apr 2, 8:43 pm, "Victor Bazarov" <v.Abaza...@com Acast.netwrote:

>WHY? Why 'char*'? Why couldn't this also be 'std::string'?

BECAUSE...Becau se ... ;-)

i have not across "std::strin g" yet. presently at Stroustrup chpater
5.

So? You have another object there already of type 'std::string'
Be consistent.

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

[Default User]

arnuld wrote:

there is no "compile-time error". after i enter input and hit ENTER i
get a run-time error. here is the code:

---------- PROGRAMME --------------
/* Stroustrup, 5.9, exercise
11

STATEMENT:
Read a sequence of words from the input. use "quit" as the
word
to terminate the input. Print the words in the order they
were
entered. don't print a word twice.modify the programme to sort
the
words before printing
them.

*/
#include<iostre am>
#include<string >

int main()
{
const std::string EOI = "quit"; // End Of
Input
char* user_input = "";

const int max_input = 1000;
char* collect_input[max_input + 1];

for(int i=0; user_input != EOI || i < max_input; ++i)
{
std::cin >user_input;
collect_input[i] = user_input;

You set user_input to point to a string literal of one character
length. There's no storage there to read any characters into. You
either have to allocate storage, or use a construct that does so
automatically, as Victor suggested (std::string).


Brian

[Bo Persson]

arnuld wrote:
::: On Apr 2, 8:43 pm, "Victor Bazarov" <v.Abaza...@com Acast.netwrote:
::
::: WHY? Why 'char*'? Why couldn't this also be 'std::string'?
::
:: BECAUSE...Becau se ... ;-)
::
:: i have not across "std::strin g" yet. presently at Stroustrup chpater
:: 5.

So PLEASE read Chapter 20 real SOON.
You know we told you to read "Accelerate d C++". There you have Chapter 1
"Working with strings". :-)
Bo Persson

[arnuld]

On Apr 2, 10:47 pm, "Bo Persson" <[e-mail] te:

So PLEASE read Chapter 20 real SOON.

OK.

You know we told you to read "Accelerate d C++". There you have Chapter 1
"Working with strings". :-)

i remember you advised "Accelerate d C++" but i just fascinated with
Stroustrup's book.

BTW, Stroustrup gave this exercise in chapter 5 (Pointer, Structures
and Arrays). hence this exercise must be solved without std::strings,
i just used it accidentally.

i am not asking for solution but asking for a "method" only, a
theoretical solution using the concepts of chapter 5. i will convert
that to code myself.

[Alf P. Steinbach]

* arnuld:

there is no "compile-time error". after i enter input and hit ENTER i
get a run-time error. here is the code:

---------- PROGRAMME --------------
/* Stroustrup, 5.9, exercise
11

STATEMENT:
Read a sequence of words from the input. use "quit" as the
word
to terminate the input. Print the words in the order they
were
entered. don't print a word twice.modify the programme to sort
the
words before printing
them.

*/

Are you sure this exercise is from the same chapter as the other
exercises you've done lately?

#include<iostre am>
#include<string >

int main()
{
const std::string EOI = "quit"; // End Of
Input
char* user_input = "";

const int max_input = 1000;
char* collect_input[max_input + 1];

for(int i=0; user_input != EOI || i < max_input; ++i)
{
std::cin >user_input;
collect_input[i] = user_input;
}

return 0;
}

'user_input' is a pointer initialized to point to (the first character
of) an empty string literal.

operator>tries to store the user's input in that literal. It writes
all over memory. Crash.

You need to store the input characters in some array. std::string does
that for you automatically. Alternatively, if you don't want to use
library classes, you can just use a suitably huge char array.

Then you need to store the strings in some array. One way, without
using std::string, is: for each read string, allocate a new char array
just large enough for the string (number of characters + 1), and store
that pointer in an array of pointers, and increment a variable that
denotes the current number of strings.

Then, I think it's best to just output the strings, don't think about
sorting yet.

--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

[Mike Wahler]

"arnuld" <ge*********@gm ail.comwrote in message
news:11******** *************@d 57g2000hsg.goog legroups.com...

there is no "compile-time error". after i enter input and hit ENTER i
get a run-time error. here is the code:

---------- PROGRAMME --------------
/* Stroustrup, 5.9, exercise
11

STATEMENT:
Read a sequence of words from the input. use "quit" as the
word
to terminate the input. Print the words in the order they
were
entered. don't print a word twice.modify the programme to sort
the
words before printing
them.

*/
#include<iostre am>
#include<string >

int main()
{
const std::string EOI = "quit"; // End Of
Input
char* user_input = "";

const int max_input = 1000;
char* collect_input[max_input + 1];

for(int i=0; user_input != EOI || i < max_input; ++i)
{
std::cin >user_input;

Hint: What does the pointer 'user_inpt' point to?

collect_input[i] = user_input;
}

return 0;
}

------------- OUTPUT -------------
[arch@voodo tc++pl]$ g++ 5.9_ex-11.cpp
[arch@voodo tc++pl]$ ./a.out
like
Segmentation fault

No, it's your fault. :-)

-Mike

[arnuld]

On Apr 3, 12:02 am, "Alf P. Steinbach" <[e-mail] rote:

You need to store the input characters in some array. std::string does
that for you automatically. Alternatively, if you don't want to use
library classes, you can just use a suitably huge char array.

Then you need to store the strings in some array. One way, without
using std::string, is: for each read string, allocate a new char array
just large enough for the string (number of characters + 1), and store
that pointer in an array of pointers, and increment a variable that
denotes the current number of strings.

Then, I think it's best to just output the strings, don't think about
sorting yet.

OK, this is what i have created what i call a "partial
implementation" , partial because i am unable to think of anything
further:

/* Stroustrup, 5.9, exercise 11

STATEMENT:
Read a sequence of words from the input. use "quit" as the word
to terminate the input. Print the words in the order they were
entered. don't print a word twice.modify the programme to sort the
words before printing them.
METHOD:

1.) we will creat ana "array of pointers" to store all of the input.

2.) we will count each word a 1 input.

3.) to take input from user we will use an "array of CHARs". each
element
of "array of pointers" will point to this input"

4.) when user will enter "quit", we will terminate the programme and
print all of the input each word per line.

*/
#include<iostre am>

int main()
{
const char* EOI = "quit";
const int max_input = 1000;
const max_wordlen = 10;
const int NULL = 0;

const char* collected_words[max_input + 1];
char** pwords = words;

const char* user_input;
while(std::cin >user_input)
{
for(char* pui = user_input; pui != '\0'; ++pui)

-------------------------------------

i can' think:

1.) what should i do to equate the input with EOI.

2.) how to copy the input into the new array and the pointing the new
array
to the "collected_word s[]"