无法通过引用将typedef结构传递给函数

Question

I'm trying to pass a custom type object to a function by reference, and I can't figure out what I could be doing wrong. I read How do you pass a typedef struct to a function? as well as other references and could swear I'm already doing exactly that. I cleared out everything else I'm doing and even this spartan code throws 5 errors. Help me, Stackexchange; You're my only hope!

The goal is simply to be able to alter the values in the array in the object.

#include <stdio.h>
#include <math.h>
typedef struct structure {
    char byte[10];
    char mod;
} complex;
void simpleInit (complex *a, char value) {//put the value in the first byte and zero the rest
    a.byte[0] = value;
    char i;
    for (i = 1; i < 10; ++i) {
        a.byte[i] = 0;
    }
    a.mod = 1;
}
void main () {
    complex myNumber;
    char value = 6;
    simpleInit (myNumber, value);
}

When I attempt to run this I get this error and 4 similar:

test2.c:10:3: error: request for member 'byte' in something not a structure or union

a.byte[0] = value;

Answer 1

a is a pointer type, so you need to de-reference it to use it. Typically that's done with the arrow operator:

a->byte[i] = 0;

Since this is just an array of bytes you can also quickly "zero" it:

memset(a, 0, 10);

Though given how important 10 is in your code you should codify that in a constant or a #define .

Answer 2

When you pass a value by reference you need to use asterisk to access al fields of the structure, for example:

(*a).byte[0] = value;

Happily you have -> as a shortcut, so this will be:

a->byte[0] = value;

Also do not forget to call the & (address of) operator when you call simpleInit .

#include <stdio.h>
#include <math.h>

typedef struct structure 
{
    char byte[10];
    char mod;
} complex;

void simpleInit (complex *a, char value) 
{
    char i;

    a->byte[0] = value;

    for (i = 1; i < 10; ++i) {
        a->byte[i] = 0;
    }

    a->mod = 1;
}

int main() 
{ 
    complex myNumber;
    char value = 6;
    simpleInit (&myNumber, value);
}