Thread: Something wrong with pointers

Does anybody have any idea why my output displays the 1d node name for both the 2d nodes "alice" and "joe" to be "bob" when my input is: "Ins alice wife", followed by "Ins joe bob". I'm really stuck on this one.

Code:

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

struct node2d {
    struct node1d *first;
    char *name;
    struct node2d *down;
};
struct node1d {
    struct node1d *next;
    char *name;
};


int print2d (struct node2d *);
struct node2d *make2dnode(char *, struct node2d *);
struct node1d *make1dnode2(char *, struct node1d *);
int dostuff(struct node2d *);



int main (int argc, char *argv[]) {
	int i;
	int x = 0;
    struct node2d *p2d=NULL;
    for (i=argc-1; i>0; i--) {
		p2d = make2dnode(argv[i], p2d);
	};
	dostuff(p2d);
	dostuff(p2d);
	print2d(p2d);
	system("PAUSE");

}
int dostuff(struct node2d *node){
	int c;
	int x=0;
	char input[1000];
	struct node2d *p2d = node;
	printf("Enter command: ");
	while((c=getchar())!='\n'){
		if (c==EOF)
			return 2;
		input[x] = c;
		x++;
	}
	input[x]= '\0';
	if(input[0]=='I' && input[1] == 'n' && input[2] == 's' && input[3] == ' '){
		int i = 4;
		int x = 0;
		int y = 0;
		int z = 0;
		char node2[1000];
		char node1[1000];
		struct node1d *p1d=NULL;
		while(input[i]!= ' '){
			node2[x] = input[i];
			x++;
			i++;
		}
		node2[x]='\0';	
		i++;
		while(input[i]!= NULL){
			node1[z] = input[i];
			z++;
			i++;
		}
		node1[x]='\0';	
		while(p2d){
			if(strcmp((p2d->name), node2)==0){
				p1d = make1dnode2(node1, p1d);
				if(p2d->first==NULL|| strcmp(p2d->first->name, p1d->name) == 1){
					p2d->first=p1d;
				}
				else{
					while(strcmp(p2d->first->name, p1d->name) != 1){
						p2d->first=p2d->first->next;
						}
						p2d->first = p1d;
						p1d->next= p2d ->first;
					
					}
			}
			p2d=p2d->down;
		}
	}
	else if(input[0] == 'R' && input[1] == 'e' && input[2] == 'm' && input[3] == ' ')
		printf("Yess");
	else{
		printf("Error");
		return 1;
	}
	system("PAUSE");
}
		

	


// Make a 2 dimensional node with down pointer next and name name
struct node2d *make2dnode(char *name, struct node2d *next){
    struct node2d *p2d;
    p2d = (struct node2d *) malloc(sizeof(struct node2d));
    p2d->first = NULL;
    p2d->name = name;
    p2d->down = next;
    return p2d;
}

int print2d (struct node2d *p2d) {
    int i=0;
	int x=0;
	struct node1d *p1d;
    while (p2d) {
		(i==0) ? printf("The first 2d-node has name: %s\n", p2d->name): printf("The next 2d-node has name: %s\n", p2d->name);
		i++;
		p1d = p2d->first;
	while (p1d) {
	    printf("\t %s has a 1d-node with name %s\n", p2d->name, p1d->name);
		x++;
		p1d = p1d->next;
	};
	p2d = p2d->down;
    };
	printf("The number of 2d nodes is %d\n", i);
	printf("The number of 1d nodes is %d\n", x);
	return 0;
}
struct node1d *make1dnode2(char *name, struct node1d *next){
	struct node1d *p1d;
    p1d = (struct node1d *) malloc(sizeof(struct node1d));
    p1d->next = NULL;
    p1d->name = name;
    return p1d;
}

So I don't see anywhere where you copy the string into the node. You have a line

Code:

p1d->name = name;

which you probably intended to do that, but doesn't (you only have one piece of memory that you keep using over and over again, and each node accumulates a pointer to that same chunk of memory). You probably want to give each node its own piece of memory that it can store a name in, separate from all the others.

I thought so too, but isn't the line "p1d = (struct node1d *) malloc(sizeof(struct node1d));" in the bottom function supposed to do that?