Thread: pointers, structures, and strings

Code:

// This is just a basic description (representation) of what I'm trying
// to do and what is happening.  I haven't programmed in C in a 
// long time and I'm trying to refresh my skills.  I understand that 
// things change and memory fails.  I'm using gcc 11.3 on a win10
// machine.  This file should be fully compliable.


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


struct x {
char *y;
};

#define MAX 100
struct x *z[MAX], *zz;


int main ()
{
char a[100];
int n=15;


// I'm using fgetc to read one char at a time into a[] from a datafile
// and parse as I go.


// My "sample" input:
a[0] = 'X'; a[1] = 'X'; a[2] = 'X'; a[3] = '\0';
printf("a = %s\n",a);


// So I use *zz to build the "local record" and this is where my
// problem is:


// Three main versions to do the same thing?? (only using one at
// a time):
//zz->y = &a[0];
//*zz->y = a[0]; *(++zz->y) = a[1]; *(++zz->y) = a[2]; *(++zz->y) = a[3]; 
strcpy(zz->y,&a[0]);


printf("zz->y = %s\n",zz->y);  // This doesn't print because I believe
                                             // the previous statements cause a
                                             // segmentation fault and the run
                                             // terminates.


// When done with building the local record, I want to assign it to 
// the next location in *z[]:
z[n] = zz;
printf("z[%i]->y = %s\n",n,z[n]->y);


//I would also like to zero out *zz and a[] after every iteration.
}
// Where am I being slopy?  What changes are needed to make this
// work?  I would prefer using strcpy.
// -- Ravenhawk

What are you trying to achieve?

This, without the need to specify an array size for the struct members?

Code:

struct x {
    char y[10];
    char y2[20];
};
 
#define MAX 100
struct x *z[MAX];

> strcpy(a,"Hello\0");
There's no need to put a \0 on the end of strings, you get one for free anyway.