macro function

Hello everyone,
I am stuck and confused about macros. I need to define a macro that returns the HOME dir of user. This is what I have so far:

Code:

---

#define GLADE_FILE { \
    char *homeDir = getenv("HOME"); \
    char *tempi = "/hello.glade"; \
    strcat(homeDir, tempi); \
    printf("%s", homeDir); \
}

---

as you can see it does not work. If I try to put it into a regular function and try to pass homeDir with return(homeDir)
I get

Quote:

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home-dir.c:19: warning: return makes integer from pointer without a cast

---

Any help would be great,
Thanks in advance.
Brad

You can't just strcat them together like that. I doubt getenv() will return enough of a buffer to guarentee that it will be safe.

In reality, you should make this into a function imo.

Quote:

---

Originally Posted by bradleyd

Hello everyone,
I am stuck and confused about macros. I need to define a macro that returns the HOME dir of user. This is what I have so far:

Code:

---

#define GLADE_FILE { \
    char *homeDir = getenv("HOME"); \
    char *tempi = "/hello.glade"; \
    strcat(homeDir, tempi); \
    printf("%s", homeDir); \
}

---

as you can see it does not work. If I try to put it into a regular function and try to pass homeDir with return(homeDir)
I get
Any help would be great,
Thanks in advance.
Brad

---

Code:

---

#define PATHLEN 256

 char mypath[PATHLEN] = { '\0' };
 char *homeDir = getenv("HOME");
 strncpy(mypath, homeDir, PATHLEN);
 strncat(mypath, "/hello.glade", PATHLEN - strlen(mypath));
 printf("%s", mypath);

---

I tried to put it into a function then call the function but I get that error. Here is the function:

Code:

---

char hd(void)
{
        char *homeDir = getenv("HOME");
    char *temp = "/hello.glade";
    strcat(homeDir, temp);
    return(homeDir);
}

---

if I substitute return(homeDir) with printf("%s",homeDir);
it works fine.

If you just want to print it without any error checking, then you could do something like this:

Code:

---

#define printglade() printf("%s/hello.glade",getenv("HOME"))

---

Since getenv() can return NULL, this is probably not a good idea.

If you need to return a string:

Code:

---

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

char *getGlade(void);

int main(void)
{
        char *szGlade = getGlade();
       
        if(szGlade)
        {
                printf("Glade directory: <%s>\n",szGlade);
                free(szGlade);
        }
        else perror("Unable to retrieve Glade directory.");
       
        return 0;
}

char *getGlade(void)
{
        char *homeDir,*temp = "/hello.glade",*szReturn = NULL;
       
        homeDir = getenv("HOME");
        if(homeDir)
        {
                szReturn = malloc(strlen(homeDir) + strlen(temp) + 1);
                if(szReturn)
                {
                        strcpy(szReturn,homeDir);
                        strcat(szReturn,temp);
                }
        }
        return szReturn;
}

---

Quote:

---

Originally Posted by bradleyd

I tried to put it into a function then call the function but I get that error. Here is the function:

Code:

---

char hd(void)
{
        char *homeDir = getenv("HOME");
    char *temp = "/hello.glade";
    strcat(homeDir, temp);
    return(homeDir);
}

---

if I substitute return(homeDir) with printf("%s",homeDir);
it works fine.

---

Your supposed to return a char pointer (char *) not a char, see MacGyver's post.

Thanks that worked, I kinda foggy on char *GetHome vs. char GetHome. If you want to return any string from a function do you always have use a pointer in declaring the function?
when you want to return a int you just int SomeNumber(void).
Just having trouble grasping that.
Thanks,
Brad

A string is a set of chars that are sequential in memory, ending with a final '\0' char. One way of representing such a data type can be done using a char array. A char array, down deep under the hood, is represented simply by a pointer to the first element of the array. This means to return a string, you have to return a char *. If you return a char, you only return one character.

ok that makes sense, thanks MacGyver.
Pointers seem to be my weak point in C.