Macro confusion

Thought these things would be simple, but apparently I don't understand them. All I want to do is have an input of a message, and the macro picks it up and prints it until you close the window. What needs to change, or am I way off in left field with this one?

Code:

---

#include <stdio.h>
#define ECHO (str) gets (message);\
                  for (i=0; i != NULL; ++i)\
                  puts(message);

int main ()
{
int i;
i=0;
printf("Enter a message:");
Echo (str);

return 0;

}

---

Code:

---

#include <stdio.h>
#define ECHO (str) gets (message);\
                  for (i=0; message[i] != NULL; ++i)\
                  putchar(message[i]);

int main ()
{
int i;
i=0;
printf("Enter a message:");
Echo (str);

return 0;

}

---

I think that was your intent. Code's pretty funky, but, I think it'll work.

Now the error message is that Echo is undefined. That makes no sense to me since right before Echo is the word define. What gives?

Case sensitive

Code:

---

#include <stdio.h>
#define ECHO (str) gets (message);\
                  for (i=0; message[i] != NULL; ++i)\
                  putchar(message[i]);

int main ()
{
int i;
i=0;
printf("Enter a message:");
ECHO(str);

return 0;

}

---

That pretty well sums it up. Thanks for helping this lowly noob.

Also you should remove space between ECHO and (

I doubt it will work because message is undefined, str is undefined (not not used by the macro, why do you need it?)

Don't use gets - use fgets (see FAQ)

this will do what u want.

Code:

---

#include <stdio.h>
#define ECHO(message) fgets(message,80,stdin);\
                        fflush(stdout);\
                  fputs(message,stdout);

int main ()
{
    int i=0;
    char str[80];
   
    printf("Enter a message:");
    ECHO(str);

    getchar();
    return 0;
}
/*my output
Enter a message:hello there
hello there
*/

---

ssharish2005

> What needs to change, or am I way off in left field with this one?
Like you should be using a function if you possibly can, not an inline macro.

Consider the mess you get into by doing say
if ( condition ) ECHO(message);

Multiline macros can be done quite well when using a do ... while(0) construct. Of course one should use functions an let the compiler decide ;)