why do i get garbage output?

[Developwebsites]

using Dev C++4
user can enter names of cities and temps,
but when it output city names i get garbage but
temps are fine.
struct Cities {
char city[];
int temp;
};
void input_names(Cities info[], int numb_cities) {

for(int t=0;t<numb_cities;t++) {
cout<<"\n\n";
cout<<"please enter name of city#"<<t+1<<": ";cin>>info[t].city;
cout<<"\nplease enter temp of city "
<<info[t].city<<": ";
cin>>info[t].temp;
}

cout<<"\n\n";
for(int t=0;t<numb_cities;t++) {
cout<<info[t].city<<" "<<info[t].temp<<"\n";
}

}//close input_names;

void main() {
int n,
numb_cities=10; //number of cities

void input_names(Cities[], int);

Cities info[numb_cities];
input_names(info, numb_cities);
}

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[Gianni Mariani]

Developwebsites wrote:

using Dev C++4
user can enter names of cities and temps,
but when it output city names i get garbage but
temps are fine.
struct Cities {
char city[];
use
string city;

instead
int temp;
};

The problem is that cin >> char [] does not allocate storage, you need
to do that. std::string does all the magic of allocating storage and
cleaning it up.

[Ron Natalie]

"Developwebsites" <de*************@aol.combatSPAM> wrote in message news:20***************************@mb-m06.aol.com...

struct Cities {
char city[];
int temp;
};
This shouldn't even compile. The array city needs a definite size. Frankly,
I suspect you're new to C++. Don't beat char arrays to death. Use the string
class.

cin>>info[t].temp;
You don't test if these finputs ail.

void main() {
main must return int.
void input_names(Cities[], int);
You don't need to repeat the declaration here.
Cities info[numb_cities];

This is also not legal. Array declarations in C++ need sizes that are constant
expressions (I bet you're using an anceint G++).

I'd recommend you get a decent C++ text. I think Koenig & Moo's Accellerated C++
will be very helpful to you.

[Developwebsites]

>>

void main() {

main must return int.

why is that?
return to where?
the program compiles fine as it is.

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[Developwebsites]

>

void input_names(Cities[], int);

You don't need to repeat the declaration >here.

I am not repeating anything.
this is a prototype.

Cities info[numb_cities];

This is also not legal. Array declarations in C++ need sizes that are
constant
expressions (I bet you're using an anceint G++).

again, it compiled fine.
1st sentence of my post:
using Dev C++4
is it old? nope, but i do have borland c++ 1.0 from 91 which does give an
error.

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[Kevin Goodsell]

Developwebsites wrote:

void main() {
main must return int.

why is that?

Because the standard requires it, as the ARM did before it.
return to where?
The calling environment.
the program compiles fine as it is.

regardless of the shortcomings of your compiler, it is required. Better
compilers will refuse it with the wrong return type.

-Kevin
--
My email address is valid, but changes periodically.
To contact me please use the address from a recent posting.

[Kevin Goodsell]

Developwebsites wrote:

void input_names(Cities[], int);
You don't need to repeat the declaration >here.

I am not repeating anything.
this is a prototype.

Yes, a prototype that appeared earlier in the code. Prototypes are
declarations.

Cities info[numb_cities];
This is also not legal. Array declarations in C++ need sizes that are
constant
expressions (I bet you're using an anceint G++).

again, it compiled fine.

Again, that doesn't matter. C++ is not "Whatever your compiler accepts".
All compilers accept some things that are not C++. gcc in particular
supports several language extensions by default. Learn how to invoke it
in standard compliant mode and it will diagnose your errors.
1st sentence of my post:
using Dev C++4

That comes with an old version of gcc.

-Kevin
--
My email address is valid, but changes periodically.
To contact me please use the address from a recent posting.

[Ron Natalie]

"Developwebsites" <de*************@aol.combatSPAM> wrote in message news:20***************************@mb-m19.aol.com...

void main() {
main must return int.

why is that?

The standard says so.
return to where?
The runtime environment.
the program compiles fine as it is.

Do not confuse tolerance with correctness.

[Developwebsites]

>>>> Cities info[numb_cities];

This is also not legal. Array declarations in C++ need sizes that are
constant

the point of my program, and the function before the above statement, was to
have the user input the number of cities.
then, the user inputs city names and temps.
how can i have a constant if i dont know the number of cities the user will
enter.
it is only logical(as my code is), it makes no sense to have a constant if the
number of cities or employees etc. is unknown.
if it could be done in BASIC why not C++?

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[Jerry Coffin]

In article <20***************************@mb-m29.aol.com>,
de*************@aol.combatSPAM says...

> Cities info[numb_cities];

This is also not legal. Array declarations in C++ need sizes that are
constant

the point of my program, and the function before the above statement, was to
have the user input the number of cities.
then, the user inputs city names and temps.
how can i have a constant if i dont know the number of cities the user will
enter.
it is only logical(as my code is), it makes no sense to have a constant if the
number of cities or employees etc. is unknown.
if it could be done in BASIC why not C++?

It _can_ be done in C++, but it's done somewhat differently. First of
all, until you know what you're doing, it's probably just about as well
to forget that C++ has arrays at all, and instead always use std::vector
for the kinds of problems where you'd use arrays in BASIC.

Using std::vector, you don't need to pre-specify the number of cities at
all -- you can simply use push_back to add each city as it's entered,
and when the user enters a blank line (or some specific string like
"end", etc.) you quit adding cities to the collection.

As far as your code being logical, well, coming from BASIC it probably
seems that way -- but to the user it will undoubtedly seem supremely
ILlogical that you demand that s/he count the cities before entering the
data. In fact, counting items in a list is exactly the sort of thing
the computer is good at, and the use should NEVER have to do!

--
Later,
Jerry.

The universe is a figment of its own imagination.

[Default User]

Developwebsites wrote:

> Cities info[numb_cities];

This is also not legal. Array declarations in C++ need sizes that are
constant

the point of my program, and the function before the above statement, was to
have the user input the number of cities.

Then you either need to use dynamic arrays (as in pointers to memory
allocated by new) or much much much preferably with std::vector.
If you want help on this newsgroup, you are going to have to stop
arguing with people and things that you don't about. There a number of
very knowledgable programmers here, so follow their advice. Don't use
the platform-specific extensions that you are told not to, instead use
the proper standard forms.

Brian Rodenborn