How to call the function including arrays of structure in main.c?

[fishwater00]

First of all, thanks!

I have a problem about the arrays of structure in C, the following is my codes:

#include "system.h"

typedef struct
{ int x, int y, int z;
short *velocity ;
float *wave ;
} Modeldim ;

void myfunction(Modeldim *submodel) ;

int main(int argc, char *argv[])
{
int X=Y=Z=1000;
int i,j,k;
int NUM=10 ;

myfunction(Modeldim *submodel);

for (i=0; i< NUM; i++)
{
/* here is the question:
"myfunction()" can split 3D model [X,Y,Z] to 10 submodels, after that, and set every submodel has its own variables, eg:
submodel[0].x, submodel[0].y, submodel[0].velocity, ...
submodel[1].x, submodel[1].y, submodel[1].velocity, ...
submodel[2].x, submodel[2].y, submodel[2].velocity, ...
and so on.
how can I call or use "subdomain[i]" in main.c?
*/
creat_model(subdomain[i].x, subdomain[i].y, subdomain[i].velocity); /*Is it right? could I do that?*/
}

};


If not, how can I call the parameters of submodel[i] in main.c? If anyone can answr it, I am HIGHLY appreciated.

[jorba101]

I don't understand most your question.

You defined:

myfunction(Modeldim *something)
{...}
 
If you call it from main, you should call it with something like:
 
int main()
{
   Modeldim var;
 
   myfunction( &var );
}
 
inside "myfunction" you can fill in the fields of var, doing:
 
myfunction( Modeldim *parameter)
{
   parameter->x = 0;
   parameter->y = 1;
 
...etc...
 
}

if what you want is a "myfunction" to populate "var" with the contents of your X, Y, Z, you should create a function:

myfunction( Modeldim *var, int x, int y, int z)

In your case I would post the question over again, maybe try starting with a shorter question.

[fishwater00]

Thank you. I am still confused about the struct.

typedef struct
{ int x;
   int y; 
   int z;
} Modeldim ;
 
void myfunction(Modeldim *submodel)
 
int main()
{ 
int x,y,z;
 
   Modeldim array[100];
 
   myfunction(Modeldim &array);    
 
 for (i=0;  i<3; i++)
    { 
        hisfunc(array[i].x, array[i].y, array[i].z) ;  
        herfunc(array[i].x, array[i].y, array[i].z) ;      /*the value of array[i].x .y .z has been passed by "myfunction(Modeldim &array)" */
     }
return;
}
 
 
void   myfunction(Modeldim *submodel)
{ 
 
   array[0].x = 10; array[0].y = 10; array[0].z = 10 ;
   array[1].x = 20; array[1].x = 20; array[1].x = 20 ;
   array[2].x = 30; array[2].x = 30; array[2].x = 30 ;
 
};
 
 

Is it right? Or still have some problem? Thank you very much.

[r035198x]

What does the compiler say?

P.S Use code tags.

[fishwater00]

I haven't tried to compile it. It is just a part of my whole codes. So I have to figure out this problem and move further.

Thanks.

[r035198x]

I haven't tried to compile it. It is just a part of my whole codes. So I have to figure out this problem and move further.

Thanks.

You should write code with a compiler close by, so that you can test your code on it. The compiler is also good at telling what errors your code may have. e.g (missing semi-colons e.t.c)

[fishwater00]

Thank you. I am going to test it.

So far I want to figure out my struct problem:

May I call the parameters of array which are included in "hisfunc" and "herfunc" in main after I define parameters in "myfunction(array)"? Does it has some "gramma" errors?

[r035198x]

Thank you. I am going to test it.

So far I want to figure out my struct problem:

May I call the parameters of array which are included in "hisfunc" and "herfunc" in main after I define parameters in "myfunction(array)"? Does it has some "gramma" errors?

Not sure I understand all that you are saying here but guessing is hardly a good approach when it comes to programming.

A good reference book/tutorial comes in handy here as well.

[fishwater00]

Thanks. I modified my codes and paste here:

 
typedef struct
{ int x, int y, int z;
  short *velocity ;
  float *wave ;
}Modeldim;
 
void a(Modeldim *domain) ;
void b(Modeldim *domain, int k) ;
void c(Modeldim *domain, int k);
 
int main()
{  int STEPS=10;
   int first = 10;
 
  Modeldim Domain;
  Domain = (Modeldim *)malloc(sizeof(Modeldim)) ;
 
  a(Modeldim Domain) ;  
 
return;
}
 
int a(Modeldim *domain)       
{ int ja;
  int lista = 5;
 
for (ja=0; ja<lista; ja++)
{
 b(domain, ja);
 c(domain, ja);
}
 
return;
}
 
int b(Modeldim *domain, int k)
{ int jb;
   int listb = 10 ;
 
   for (jb=0; jb<listb; jb++)
          {
           domain[k].x[jb] = 1;
           domain[k].y[jb] = 2;
           domain[k].z[jb] = 3;
          }
 
return;
}
 
int c(Modeldim *domain, int k)
{ int jc;
  int listc =20 ;
 
 for(jc=0; jc<listc; jc++)
       {
       domain[k].velocity[jc] = 5;
       domain[k].wave[jc] = 12.00 ;
      }
return;
}
 

In this code, I try to call struct in "b()" and "c()" from subfunction "a()" which is in "main.c". Is it reasonable? All functions are in one same file called main.c.

How can I do if I declare the struct as globe struct, and call those functions which are in different files, such as b.c and c.c file? I hope I describe my question clearly.

Thank you very much.

[jorba101]

In this code, I try to call struct in "b()" and "c()" from subfunction "a()" which is in "main.c". Is it reasonable? All functions are in one same file called main.c.

There is no problem in that.

How can I do if I declare the struct as globe struct, and call those functions which are in different files, such as b.c and c.c file? I hope I describe my question clearly.

Just that: put your b() function in a separate file called b.c. Afterwards, you have to tell main.c which prototype has b(). To do that, you can just type the prototype of the function, but the typical way would be putting the prototype in a b.h file, and then include it in main.c (#include "b.h")

To do that there is no need to declare your Modeldim as global, but you do need to place in b.c the typedef for Modeldim (otherwise the compiler won't know whats modeldim when trying to compile b()). A more convenient way of doing this would be placing your typedef for modeldim in a separate file (e.g. modeldim_typedef.h), and including it in all files (b.c, c.c, main.c) that use it (#include "modeldim_typedef.h").

[fishwater00]

Great! Thanks a lot.

Another question is about memory allocation.

If I don't use struct, just define like:

float velocity, wave ;
 

I need to allocate dynamic memory for them:

velocity = my_malloc(NX, NY, NZ, sizeof(float)) ;    
wave = my_malloc((NX, NY, NZ, sizeof(float)) ;
 
/* my_malloc is a function which can allocate dynamic memory for them */
 

If in struct, do I still need to allocate memory space for them separately? or just use

Domain=(Modeldim *)malloc(sizeof(Modeldim)) ;
 

Because in this "Modeldim" struct, the parameters I need to define are 2D and 3D, some are 1D array. I am worry about the memory problems. Thanks again.

[jorba101]

If I don't use struct, just define like:

float velocity, wave ;
 

I need to allocate dynamic memory for them:

velocity = my_malloc(NX, NY, NZ, sizeof(float)) ;    
wave = my_malloc((NX, NY, NZ, sizeof(float)) ;
 
/* my_malloc is a function which can allocate dynamic memory for them */
 

If in struct, do I still need to allocate memory space for them separately? or just use

Domain=(Modeldim *)malloc(sizeof(Modeldim)) ;
 

Because in this "Modeldim" struct, the parameters I need to define are 2D and 3D, some are 1D array. I am worry about the memory problems. Thanks again.

When you are declaring something like:

float velocity, wave ;

You are already telling at compile time which memory is using each variable (i.e. a float), so there is no need to do a malloc (actually, you can't do it).

In this case, you could use a malloc if you did:

float *velocity, *wave;

Afterwards you would do

velocity = malloc( N * sizeof( float) );

Which would reserve memory for N floats pointed at the very beginning by velocity.

Note that dynamic allocation has only sense if you can't know at compile-time what is the number of float elements you need in velocity (e.g., in the example above, N is something you only know at run-time). If you know the value of N at compile-time, you have no need of using malloc(), since you can simply do an array:

float velocity[N];

Thus, the same for Modeldim. You should use a malloc() if you don't know at compile time how many Modeldim's you need. If you DO know it at compile-time, then simply do:

Modeldim myModelDim;

[fishwater00]

Thank you. I use gcc to compile it ( I call it "try.c":

typedef struct
{int x, int y, int z;
  short *velocity ;
  float *wave ;
}Modeldim;
 
void a(Modeldim *domain) ;
void b(Modeldim *domain, int k) ;
void c(Modeldim *domain, int k);
 
int main()
{  int STEPS=10;
   int first = 10;
 
  Modeldim Domain;
  Domain = (Modeldim *)malloc(sizeof(Modeldim)) ;
 
  a(Modeldim Domain) ;  
 
return;
}
 
void a(Modeldim *domain)       
{ int ja;
  int lista = 5;
 
for (ja=0; ja<lista; ja++)
{
 b(domain, ja);
 c(domain, ja);
}
 
return;
}
 
 
void b(Modeldim *domain, int k)
{ int jb;
   int listb = 10 ;
 
   for (jb=0; jb<listb; jb++)
          {
           domain[k].x[jb] = 1;
           domain[k].y[jb] = 2;
           domain[k].z[jb] = 3;
          }
 
return;
}
 
 
void c(Modeldim *domain, int k)
{ int jc;
  int listc =20 ;
 
 for(jc=0; jc<listc; jc++)
       {
       domain[k].velocity[jc] = 5;
       domain[k].wave[jc] = 12.00 ;
      }
return;
}
 
 

and use gcc:

gcc try.c
 

but some errors come out

try.c:2: error: syntax error before ‘int’
try.c:2: warning: no semicolon at end of struct or union
try.c:5: error: syntax error before ‘}’ token
try.c:5: warning: data definition has no type or storage class
try.c:7: error: syntax error before ‘*’ token
try.c:8: error: syntax error before ‘*’ token
try.c:9: error: syntax error before ‘*’ token
try.c: In function ‘main’:
try.c:15: error: syntax error before ‘Domain’
try.c:16: error: ‘Domain’ undeclared (first use in this function)
try.c:16: error: (Each undeclared identifier is reported only once
try.c:16: error: for each function it appears in.)
try.c:16: error: syntax error before ‘)’ token
try.c:18: error: syntax error before ‘Domain’
try.c: At top level:
try.c:23: error: syntax error before ‘*’ token
try.c: In function ‘a’:
try.c:29: error: ‘domain’ undeclared (first use in this function)
try.c: At top level:
try.c:37: error: syntax error before ‘*’ token
try.c: In function ‘b’:
try.c:43: error: ‘domain’ undeclared (first use in this function)
try.c:43: error: ‘k’ undeclared (first use in this function)
try.c: At top level:
try.c:52: error: syntax error before ‘*’ token
try.c: In function ‘c’:
try.c:58: error: ‘domain’ undeclared (first use in this function)
try.c:58: error: ‘k’ undeclared (first use in this function)
 

What's wrong here? I do not find any syntax error from line 2. it looks something wrong with struct.

[jorba101]

Try declaring it like this:

typedef struct
{
int x, y, z;
short *velocity ;
float *wave ;
} Modeldim;

[selvijeyaraman]

Please correct the following mistakes.
1. While calling methods, u shd not use the structure name.
2. int x, int y, int z; Use ; to split declaration or use like
int x,y,z
3. U can allocate memory for the pointer varilable only.
4. Instead of

domain[k].x[jb] = 1;
domain[k].y[jb] = 2;
domain[k].z[jb] = 3;

Try this. Because in structure u've declared x,y,z as interger variable not an array.

domain[k].x = 1;
domain[k].y = 2;
domain[k].z = 3;



Please refer C books.

[fishwater00]

Please correct the following mistakes.
1. While calling methods, u shd not use the structure name.

Thanks. What do you mean "calling method"?

If I call function "a( )" from main, I can use

void a(Model *domain, int t)  /* domain is the name of struct */
 

It should be right, isnt it?

[selvijeyaraman]

Just call the method inside main as a(Domain);