I have a structure declared in main and I want this to be avaliable to another function so I assume I need to pass a pointer to the other function ? how is this done.
that was my attempt but I know its completely wrong any help will be appreciated.Code:otherfunction(*ptr); int main () { typedef struct test { char test1[25]; int test2[20]; }tst[10]; otherfunction(*tst) }
EDIT: POSTED TOO EARLY ACCIDENTALLY
Firstly, it is probably best to keep the structure definition outside of main then create the declaration in main.
This code will pass the actual array of structures created. To create and pass a single structure:Code:/* structure definition */ struct test { char test1[25]; int test2[20]; }; /* function prototype */ int otherfunction(struct test[]); int main () { struct test a[10]; otherfunction(a); return 0; }
Code:/* structure definition */ struct test { char test1[25]; int test2[20]; }; /* function prototype */ int otherfunction(struct test); int main () { struct test a; otherfunction(a); return 0; }
Last edited by Zainny; 08-13-2003 at 06:32 AM.
Beware the fury of a patient man.
Do I not need to pass a pointer if I wish to edit the contents of the sturcture in the other function?
No.Do I not need to pass a pointer if I wish to edit the contents of the sturcture in the other function?
The most common reason for passing a pointer to a structure rather than the structure itself for a function call is to conserve space on the stack.
Beware the fury of a patient man.
This is wrong. If you want to modify the contents of the structure in another function, you must pass a pointer. Otherwise, a bitwise copy is done and you'll just be modifying the copy.Originally posted by Zainny
No.
The most common reason for passing a pointer to a structure rather than the structure itself for a function call is to conserve space on the stack.
Note the * in the prototype and the & in the function call.Code:/* structure definition */ struct test { char test1[25]; int test2[20]; }; /* function prototype */ int otherfunction(struct *test); int main () { struct test a; otherfunction(&a); return 0; }
Thanks thats what I wanted.
Doh! Just shows, you shouldn't post after a hard night of drinkingThis is wrong. If you want to modify the contents of the structure in another function, you must pass a pointer. Otherwise, a bitwise copy is done and you'll just be modifying the copy.
Apologies for the incorrect information Gav D.
Beware the fury of a patient man.
GCC has a problem with
int otherfunction(struct *test);
it says error before *. is the * definatly suposed to be there?
Should be:
Code:int otherfunction(struct test *);
Beware the fury of a patient man.
Oops, sorry about the misplaced asterisk. Looks like I wasn't paying full attention either.
can anyone tell me why GCC give me '29 : invalid type for argument 1 of get response? Dont ask me why I need the pointer for the structure in getresponse, I do I just havent written the code for it yet. Thanks
Code:int sortentries(); struct phonebook { char Name[25]; int No[20]; }; int getresponse (struct phonebook *); int main () { int cnt; struct phonebook PBook[10]; for (cnt=0;cnt<clr;cnt++) puts(""); gotoxy (0,0); displaymenu(); getresponse(*PBook); return (0); } int displaymenu () { puts ("\nP System"); puts ("-------------------"); puts ("\n1) Add Entry"); puts ("2) Delete Entry"); puts ("3) Find Entry"); puts ("4) View List"); puts ("5) Sort Entries"); puts ("\nQ) Quit"); puts ("\nEnter Selection"); return(0); } int getresponse (struct phonebook *) { char chrResponse; scanf("%c",&chrResponse); switch (chrResponse) { case '1': addentry(); return(0); case '2': delentry(); return(0); case '3': findentry(); return(0); case '4': viewlist(); return(0); case '5': sortentries(); return(0); case 'Q': puts("Quit"); return(1); } } int addentry() {} int delentry() {} int findentry() {} int viewlist() {} int sortentries() {}
