Question

C Question: How do you pass structures (or structure fields) as function parameters?

Answer 1

use pass by pointer....
struct mystruct {
...
};

void passthestruct(struct mystruct* p)
{
// use the structure pointer
}

pass by value:
void passstructbyvalue(struct mystruct v)
{
}


just like passing variable to function

Answer 2

I declared my structures using typedef:

typedef struct {
char OrigCurr[4];
char WantCurr[4];
float ExRate;
} STRUCTTYPE_Rates;

typedef struct {
char User[31];
char Pass[31];
char Role[14];
} STRUCTTYPE_Users;

STRUCTTYPE_Rates STRUCT_Rates[100];
STRUCTTYPE_Users STRUCT_Users[100];

I'm trying to pass the parameter by pointer:

int TXTDATA_Read_Rates(STRUCTTYPE_Rates* STRUCT_Rates, FILE *STREAM_Rates) {
//blahblah
}

int TXTDATA_Read_Users(STRUCTTYPE_Users* STRUCT_Users, FILE *STREAM_Users) {
//blahblah
}

Now when I compile, i get the following error message, for both lines above:

error: expected ‘)’ before ‘*’ token

What am I doing wrong?

Answer 3

I'm using gcc btw. I'm required to.

Answer 4

Also, my struct declarations are in the main function. Is there a way to do what I want without making the structures global?

Answer 5

change the structure declarations as...
typedef struct _mystruct {
fields...
} mystruct;

here the error maybe due to structure name is not declared.

Alternate:
struct _mystruct {
fields
};

typedef struct _mystruct mystruct;

Answer 6

I've got these errors from trying to compile the attached .c file:

test.c:74: error: expected ‘)’ before ‘a’
test.c:99: error: expected ‘)’ before ‘STRUCT_Users’
test.c:153: error: expected ‘)’ before ‘STRUCT_Users’
test.c:175: error: expected ‘)’ before ‘STRUCT_Users’
test.c:210: error: expected ‘)’ before ‘STRUCT_Users’