structure copy
I have been working on a home work assignment for a while. Now I am trying to copy a structure to another structure.
The class book says that you can copy a structure using =. I cannot get that method to work.
This is my structure.
I have filled Word and now want to copy that contents to WordCopy.Code:#define MAXWORDS 1000 typedef struct { char Words[88]; }UniqueWords;
Code:UniqueWords Word[MAXWORDS]; UniqueWords WordCopy[MAXWORDS];
So just iterate over every element in Word and do a strcpy of Word[i].words into WordCopy[i].words.
Although, I don't understand why WordCopy[i] = Word[i] does not cut it for you.
1. Get rid of gets(). Never ever ever use it again. Replace it with fgets() and use that instead.
2. Get rid of void main and replace it with int main(void) and return 0 at the end of the function.
3. Get rid of conio.h and other antiquated DOS crap headers.
4. Don't cast the return value of malloc, even if you always always always make sure that stdlib.h is included.
Works for me.
Code:#include <stdio.h> #include <string.h> struct prod { int height; char name[5]; }; int main(int argc, char *argv[]){ int i, j ; struct prod word[5] ; struct prod wordcopy[5] ; for (i = 0 ; i < 5 ; i++) { word[i].height = i+1 ; strcpy(word[i].name,"Dino") ; } for (i = 4, j = 0 ; i >= 0 ; i--, j++ ) { wordcopy[i] = word[j] ; } for (i = 0 ; i < 5 ; i++) { printf( "height: word=%d, wordcopy=%d\n", word[i].height, wordcopy[i].height) ; printf( "name : word=%s, wordcopy=%s\n", word[i].name, wordcopy[i].name) ; } return 0; }
Mainframe assembler programmer by trade. C coder when I can.
Just use the = operator.
Code:#include <stdio.h> #include <string.h> typedef struct { char Words[88]; } UniqueWords; UniqueWords w0={"HEY"}, w1 = {"Hello Struct Copy!"}; int main (void) { printf ("w0.Words = \"%s\"\n",w0.Words); printf ("w1.Words = \"%s\"\n",w1.Words); printf ("Swapping structs...\n\n"); w0 = w1; strcpy (w1.Words,"Goodbye."); printf ("w0.Words = \"%s\"\n",w0.Words); printf ("w1.Words = \"%s\"\n",w1.Words); return 0; }
As the book said, you can certainly copy a structure like this:
Maybe you copied the array of structures instead of the structure itself like this:Code:WordCopy[i]=Word[i];
Of course, it is wrong.Code:WordCopy=Word;
sorry about my poor English.
just "=" is ok for each array element;
you can also use memcpy, memcpy(WordCopy,Word,MAXWORDS);
If you want to copy array of struct, you can use either loop and assign or just use memcpy() function.
Code:for(i = 0; i < n; i++) { src[i] = dst[i]; } // or using memcpy memcpy(src,dst, n * sizeof(*src) );
Thank you all for your help. I will be able to move onto the next step of this assignment.
Thanks again.
