Lookup in lists

This is a discussion on Lookup in lists within the C Programming forums, part of the General Programming Boards category; I am just practicing my list writing skills. I wrote a few list funcs, such as addnew, lookup etc. However, ...

  1. #1
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    Dec 2007
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    67

    Lookup in lists

    I am just practicing my list writing skills. I wrote a few list funcs, such as addnew, lookup etc.
    However, when it comes to implementing lookup in main funcs i am a bit cunfused as to what parameters i should use. here is my code:
    Code:
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <ctype.h>
    
    typedef struct List { char *name; int value; struct List *next;} List;
    
    List *newitem (char *name, int value)
    {
    	List *newp;
    	newp = (List *)calloc(1,sizeof(List));
    	newp -> name = name;
    	newp -> value = value;
    	newp -> next = NULL;
    	return newp;
    }
    
    List *addfront (List *listp, List *newp)
    {
    	newp -> next = listp;
    	return newp;
    }
    
    List *addtoend (List *listp, List *newp)
    {
    	List *p;
    	if (listp == NULL)
    		return newp;
    	for (p = listp; p-> next != NULL; p = p -> next)
    	p -> next = newp;
    		return listp;
    }
    
    List *lookup (List *listp, char *name)
    {
    	for ( ;listp != NULL; listp = listp -> next)
    		if (strcmp(name, listp -> name) == 0)
    		return listp;
    	return NULL;
    }
    
    int main (void)
    {
    	char s;
    	char j[15];
    	List *K = NULL;
    	while (s != '.'){
    		s = getchar();
    	K = newitem (s,K);
    	}
    	printf("Type a name please:");
    	scanf("%s", j);
    	lookup(
    }
    what would i need to put into the lookup func after a name is read into the array?
    thanks

  2. #2
    Algorithm Dissector iMalc's Avatar
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    You haven't properly constructed the list yet, so lookup wont work. You haven't got the right parameters to newItem, and you aren't calling addfront or addtoend to build up a list. You have to fix that before you can start trying to get lookup to work.

    You might want a char array in the List struct instead of just a char*.
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