pointer to struct

[povoação]

can´t understand why the program above not works.
thanks all
#include <stdio.h>
#include <stdlib.h>

#define SIZE 3

struct peoples
{
int code;
char name[20];
float value;
};

int main()
{
int a;
struct peoples *people;
people=(struct peoples *)malloc(SIZE*s izeof(struct peoples));
for(a=0;a<SIZE; a++)
{
people->code=a;
scanf("%s",peop le->name);
scanf("%f",peop le->value);
people++;
}
for(a=0;a<SIZE; a++)
{
printf("%d",peo ple->code);
printf("%s",peo ple->name);
printf("%f",peo ple->value);
people++;
}
}

[Default User]

povoação wrote:

It´s true. I saved .c and now compiles. I´m using Dev-C++ now.
Can help me to fix the program to work with pointers notation?

Please don't top-post. Your replies belong following or interspersed
with properly trimmed quotes. See the majority of other posts in the
newsgroup, or:
<http://www.caliburn.nl/topposting.html >

[Fred Kleinschmidt]

On Dec 6, 4:10 pm, "matevzb" <mate...@gmail. comwrote:

povoação wrote:

can´t understand why the program above not works.For many reasons.

people=(struct peoples *)malloc(SIZE*s izeof(struct peoples));
for(a=0;a<SIZE; a++)
{
people->code=a;
scanf("%s",peop le->name);
scanf("%f",peop le->value);
people++;
}You're incrementing people (pointer to struct peoples), which after
the

first for loop points to where? You'd be better of with:
people[a].code = a;
Secondly, scanf() arguments should be pointers so use:
scanf ("%f", &people[a].value);
For char arrays, you can use either people[a].name or
&people[a].name[0]. Some prefer the second version.
Thirdly, you're not checking for scanf() return values. If someone
doesn't enter a float when you expect it, your program will misbehave.
Also, your people[a].name is limited to 20 characters, it won't work if
someone enters more than that - check the scanf() man page.

}
for(a=0;a<SIZE; a++)
{
printf("%d",peo ple->code);
printf("%s",peo ple->name);
printf("%f",peo ple->value);
people++;
}Again, don't increment people, use people[a]. Outputting a newline
now

and then may also be a good thing.

"povoação" <ok*****@gmail. comwrote in message
news:11******** **************@ 80g2000cwy.goog legroups.com...

I modified to people[a] instead pointer and works well, but I´m
learning pointers and I can´t understand cause was not working with
pointer.

in your first loop, you included:
for(a=0;a<SIZE; a++) {

people++;
}

So, where does "people" now point?

Then your second loop:

for(a=0;a<SIZE; a++) {
printf("%d",peo ple->code);
people++;
}

Just because you began a new loop, this does not
mean the "people" magically again points to the
original place.

If you insist on using pointers, try:

struct peoples *p = people;
for(a=0;a<SIZE; a++) {
scanf("%s",p->name);
scanf("%f",&p->value);
p++;
}
p = people; /* resets to point to origin of allcated structs */
for(a=0;a<SIZE; a++) {
...
p++;
}

(still contains problems pointed out by others)

Fred L. Kleinschmidt
Boeing Associate Technical Fellow
Technical Architect, Software Reuse Project

[Keith Thompson]

Ben Pfaff <bl*@cs.stanfor d.eduwrites:

"povoação" <ok*****@gmail. comwrites:

>Can help me to fix the program to work with pointers notation?

If a problem is easily solved using array notation, then there is
no need to solve it another way.

Unless the actual problem is learning to use pointer notation.

--
Keith Thompson (The_Other_Keit h) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <* <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.

[CBFalconer]

Ben Pfaff wrote:

"ls@qustation.c om" <ls******@gmail .comwrites:

You only have on struct and one pointer.

Read his code again. He allocates an array of SIZE structs.

And then uses it as if it held 2 * SIZE structs. Boom.

--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net>

[povoação]

thanks all. Now works with pointers. Thanks for the tips too.

On Dec 6, 11:03 pm, CBFalconer <cbfalco...@yah oo.comwrote:

Ben Pfaff wrote:

"l...@qustation .com" <lsear...@gmail .comwrites:

You only have on struct and one pointer.

Read his code again. He allocates an array of SIZE structs.And then uses it as if it held 2 * SIZE structs. Boom.

--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home .att.net>