struct ptrs to struct ptrs

[lolguy]

i just wanted to ask if i can like do from struct ptrs to struct ptrs like

#include <stdio.h>
void readerr(char *prompt,char *name_combined,int name_size);
#define name_size 100
struct firstname
{
	char first[name_size];
}typedef struct firstname emp;
struct lastname
{
	char lastname1[name_size];
}typedef struct lastname emp2;
void readerr(char *prompt,char *name_combined,int name_size)
{
	fputs(prompt,stdout);
	fgets(name_combined,name_size,stdin);
	fflush(stdin);
}
int main(void)
{
    char question[]="Please enter your first name: ";
    char question1[]="Please enter your last name: ";
	emp * first2;
    emp2* lastname2;
    readerr(question,first2->first,name_size);
    readerr(question1,lastname2->lastname1,name_size);
    printf("Now full name is %s",first2->first->lastname2);
    return 0;
}

can someone explain like struct ptrs within struct ptrs
thanks

[laserlight]

test.c:7: error: two or more data types in declaration of `emp'
test.c:11: error: two or more data types in declaration of `emp2'
test.c:12: error: syntax error before numeric constant
test.c: In function `readerr':
test.c:13: error: number of arguments doesn't match prototype
test.c:2: error: prototype declaration
test.c:14: error: `prompt' undeclared (first use in this function)
test.c:14: error: (Each undeclared identifier is reported only once
test.c:14: error: for each function it appears in.)
test.c:15: error: `name_combined' undeclared (first use in this function)
test.c: In function `main':
test.c:26: error: request for member `lastname2' in something not a structure or union

[MK27]

Do you mean something like this:

#include <stdio.h>
#include <string.h>

struct info {
	char data[256];
	int ID;
};

struct wrapper {
	char source[64];
	char dest[64];
	struct info content;
};

void dostruct (struct wrapper* here) {
	printf("DATA: %s\nID: %d\n",here->content.data,here->content.ID);
}

int main () {
	struct wrapper example;
	strcpy(example.content.data,"hello world");
	example.content.ID=667;
	dostruct(&example);
	return 0;
}

Beware the mixed notation in dostruct(): here->content.data

If struct wrapper used a struct info*, I would have had to allocate it and then in dostruct() there would be the more normative "here->content->data". That is more normative because it's more useful to use a pointer in a wrapper like this. Another useful method is to use an int member "length" in struct info to indicate the length of the data inside, especially if "data" were a char* into a block which is not null terminated -- as is sometimes the case with network packets.

[Salem]

100+ posts, and still using fflush(stdin).
This is going to take a while

[lolguy]

oh yah mixed notation after that . yes i got it now well for fflush(stdin); is just a hobby but before program done i do getchar(); but sometimes problems appear espicially for nums i dunno how to avoid that

[Salem]

You avoid it by NOT mixing input styles within your program. Chaotic choices of gets(), scanf(), getchar() etc result in a mess of the input stream.

Use fgets() EVERY time, then use sscanf() or anything else you like to examine the line of input in memory.