Thread: Filling an Array of Structures

Hello,

In the project I'm currently working on, I'm trying to fill up an array of structures from stdin. The input contains names, and I want to put each name into an array of structures. Each structure has a name and an int associated with it. Here is what I have:

Code:

 #include <stdio.h>
 #include <string.h>
 
 #define MAX_PERSON 100
 
 struct person {
    char* name;
    int num;
 };
 
 main(int argc, char *argv[]) {
    char buf[BUFSIZ];
    char *tok;
    int lineNum = 1;
    int pos = 0;
    FILE *fp;
    char *names[MAX_PERSON];
    struct person people[MAX_PERSON];
    
    while ( fgets(buf,BUFSIZ,stdin) != NULL ) {
       tok = strtok(buf," ");
       people[pos] = {tok,lineNum};
       pos++;
       tok = strtok(NULL,"\n");
       people[pos] = {tok,lineNum};
       pos++;
       lineNum++;
    }
    
    
 }

When I try to compile this, it says there is a parse error before the first { in the lines with people[pos] on it. I'm not entirely sure how to insert an entry into the array of structures. Can someone help me?

I fixed a few things, left stuff I had no idea why you did what you did.

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 #define BUFSIZ 256
#define MAX_PERSON 100
#define NM_SIZE 80 
 struct person {
    char name[NM_SIZE];
    int num;
 };
 
 main(int argc, char *argv[]) {
    char buf[BUFSIZ];
    char *tok;
    int lineNum = 1;
    int pos = 0;
    FILE *fp;
    char *names[MAX_PERSON];  /* what is this for ? */
    struct person people[MAX_PERSON];
    
    while ( fgets(buf,BUFSIZ,stdin) != NULL ) {
       tok = strtok(buf," ");
       memset(people[pos].name,0x00,NM_SIZE);
       strcpy(people[pos].name = {tok,lineNum};     
       tok = strtok(NULL,"\n");
       people[pos].num =atoi(tok); 
       pos++;
       lineNum++;
    }
    
    
 }

Ok, here's what I have now. It compiles correctly, but I get a Segmentation Fault when I run it.

Code:

#include <stdio.h>
 #include <string.h>
 
 #define MAX_PERSON 100
 
 struct person {
    char* name;
    int num;
 };
 
 main(int argc, char *argv[]) {
    char buf[BUFSIZ];
    char *tok;
    int lineNum = 1;
    int pos = 0;
    int i;
    FILE *fp;
    struct person people[MAX_PERSON];
    
    while ( fgets(buf,BUFSIZ,stdin) != NULL ) {
       tok = strtok(buf," ");
       strcpy(people[pos].name,tok);
       people[pos].num = lineNum;
       pos++;
       tok = strtok(NULL,"\n");
       strcpy(people[pos].name,tok);
       people[pos].num = lineNum;
       pos++;
       lineNum++;
    }
    
    for (i = 0; i < pos; i++) {
       printf("%s %d\n", people[i].name,people[i].num);
    }
 }

Any ideas why I'm getting a segmentation fault?

It seems to be in the strcpy part of the code.

Code:

struct person {
    char* name;
    int num;
 };

That's why

change char *name;
to char name[80]; -- or whatever

Ok, I'm filling up the array correctly. Now I need to qsort and then do a binary search on it. However, I'm having difficulty using bsearh. Here is my code:

Code:

 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
 
 #define MAX_PERSON 100
 #define MAX_NAME 10
 
 struct person {
    char name[MAX_NAME];
    int num;
 };
 
 int compare(const void *p, const void *s) {
    return strcmp(((struct person*)p)->name, ((struct person*)s)->name);
 }
 
 int compare2(const void *p, const void *s) {
    return strcmp((char *)p, ((struct person*)s)->name);
 }
 
 main(int argc, char *argv[]) {
    char buf[BUFSIZ];
    char *tok;
    char *result;
    char lookup[3];
    int lineNum = 1;
    int pos = 0;
    int i;
    FILE *fp;
    struct person people[MAX_PERSON];
    struct person *match;
    
    while ( fgets(buf,BUFSIZ,stdin) != NULL ) {
       tok = strtok(buf," ");
       strcpy(people[pos].name,tok);
       people[pos].num = lineNum;
       pos++;
       tok = strtok(NULL,"\n");
       strcpy(people[pos].name,tok);
       people[pos].num = lineNum;
       pos++;
       lineNum++;
    }
    
    qsort(people,pos,sizeof(struct person), compare);
    
    if ( (fp = fopen(argv[1],"r")) == NULL) {
       fprintf(stderr,"Cannot open %s\n",argv[1]);
       exit(1);
    }
    
    while ( fgets(buf,BUFSIZ,fp) != NULL ) {
       tok = strtok(buf," ");
       strncpy(lookup,tok,3);
       match = (struct person*)bsearch(lookup,people,pos,sizeof(struct person),compare2);
       printf("%s",match->name);
    }
       
       
    for (i = 0; i < pos; i++) {
       printf("%s %d\n", people[i].name,people[i].num);
    }
 }

I have no idea if I'm using bsearch right or not. What I want to do is take lines from a file like this:

Ann: Ken Jim Ian Len
Bev: Len Ian Jim Ken
Cat: Ken Ian Jim Len
Dot: Ian Len Ken Jim
Ian: Bev Cat Ann Dot
Jim: Dot Cat Ann Bev
Ken: Bev Cat Ann Dot
Len: Dot Bev Ann Cat

Then I want to bsearch through my people array and get the number that goes with that person. Can someone tell me how to use bsearch right? I know I'll have to use strtok more than once in the second while loop, but I was just testing bsearch. I'm getting a segmentation fault at the moment.