在C中进行字符串数组搜索

Question

I'm trying to figure out how to search a list of names that are inputted into a string array. If the name entered is part of the original array, then the search function should return the position of the string in the array; if the string is not found, it should return -1. If -1 is returned then I want to be able to print out "not found", which doesn't seem like it would be too hard to figure out, but if the name is found, I want to be able to print out the position at which the name is found.

Here is my code, obviously I'm new to this, so I might have butchered how this is supposed to be done. The rest of my code seems to work fine, but it's this function that has me at a loss.

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

#define MAX_NAMELENGTH 10
#define MAX_NAMES 5
void initialize(char names[MAX_NAMES][MAX_NAMELENGTH]);
int search(char names[MAX_NAMES][MAX_NAMELENGTH],int i,Number_entrys);
int main()
{
    char names[MAX_NAMES][MAX_NAMELENGTH];
    int i;
    initialize(names);
    search(names,i,Number_entrys);
    search_result= search(names,i,Number_entrys);
    if (search_result==-1){
        printf("Found no names.\n");
    }
    if(search_result==0){
       printf("Name found");
    }    getch();
    return 0;
}

void initialize(char names[MAX_NAMES][MAX_NAMELENGTH])
{
    int i, Number_entrys;

    printf("How many names would you like to enter to the list?\n");
    scanf("%d",&Number_entrys);

    if(Number_entrys>MAX_NAMES){
               printf("Please choose a smaller entry\n");
    }else{
        for (i=0; i<Number_entrys;i++){
            scanf("%s",names[i]);
        }
    }
    for(i=0;i<Number_entrys;i++){

        printf("%s\n",names[i]); 
    }
}

int search(char names[MAX_NAMES][MAX_NAMELENGTH],int i)
{
    int j, idx;
    char name[MAX_NAMELENGTH];
    printf("Now enter a name in which you would like to search the list for:");
    scanf("%s", name);

    for(x = 0; x < Number_entrys; x++) {
        if ( strcmp( new_name, names[x] ) == 0 ){
            /* match, x is the index */
            return x;
        }else{
            return -1;   
        }
    }
}

Answer 1

You means like this:

int search(char names[MAX_NAMES][MAX_NAMELENGTH], int i)
{
     int j, idx;
     char name[MAX_NAMELENGTH];
     printf("Now enter a name in which you would like to search the list for:");
     scanf("%s", name);

     idx = -1;
     for(j = 0; j < i; j++){
         if(strstr(names[i], name) != NULL){
             idx = j;break;
         }
     }
     return idx;
}

Answer 2

There are several problems here.

The purpose of search is to ask the user to enter a single name to be searched for. So why is

 char new_name[MAX_NAMES][MAX_NAMELENGTH];

You need only a single array

 char new_name[MAX_NAMELENGTH];

Then you have a loop you just go round once, so you don't need a loop

 scanf("%s",new_name);

would be enough. This feels like you have copied the code you used to fill your array of names, but haven't really understood its essence.

Another problem is that you have no control on how long a name the user might enter. What would happen if the user typed a very long name? You'd over-fill the array and your program will probably crash and burn. Read this article to learn about how to control this.

To be really pedantic you should also check the return code from scanf, you are expecting to read one item so the return value should be 1, anything else would be an error.

Then you are trying to use strstr(), to look through an array of char arrays. The strstr documentation says that its purpose is to search for a substring within a string rather than search through an array of strings.

So instead just search the array by hand

/* what is i? the number of items used in the array? */
for(x = 0; x < i; x++) {
    if ( strcmp( new_name, names[x] ) == 0 ){
        /* match, x is the index */
        return x;
    }
}
/* here with no match */
return -1;

In your main

int search_result;

search_result = search( /* etc */ );

if ( search_result == -1 ) {
     /* print "not found" here */
} else {
     /* print something else */
}

Answer 3

(8) ...
Maybe we'll turn it all around
'Cause it's not too late
It's never too late!! (8)
:) !

---

Sorry about the song ^_^... oh Well, I was having fun with this question for a couples of minutes, I hope this code help you out a little more, with regards:

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


/* return array of indexs */

int*
search(const char *list, size_t slen, const char **arr_names, size_t arrlen)
{
    int *arr_idx;
    int j,i,idx;

    i=idx=0;

    arr_idx = malloc(sizeof(int)*arrlen+1);

    if(!arr_idx)
        exit(EXIT_FAILURE);

    for(i=0; i<slen; i++) {
        for(j=0; j<arrlen ; j++) {
            if(!strncmp(&list[i], &arr_names[j][0], strlen(arr_names[j]))) {
                arr_idx[idx] = j;
                idx++;
            }
        }
    }

    arr_idx[idx] = -1; /* -1 terminated array */
    if(!idx) {
        free(arr_idx);
        return NULL; /* found no names */
    }

   return arr_idx;
}
/* I'm a sick [something], nul terminated strings :P */
const char *string   = "My favorite artists: ATB, Nujabes and Bonobo also Aphex Twins is nice, along with Trapt and Breaking Benjamin.\0";
const char *names[] = {"ATB\0", "Scifer\0", "Aphex\0", "Bonobo\0", "Nujabes\0", "Tipper\0"};
#define N_NAMES 6

int
main(void)
{
    int i;
    int *array;

    array = search(string, strlen(&string[0]), names, N_NAMES);

    if(!array) {
        puts("Found no names.\n");
        return EXIT_SUCCESS;
    }

    printf("Names found: ");
    for(i=0; array[i]!=-1; i++)
        printf("%s,", names[array[i]]);

    printf("\b \n");
    free(array);  /* important */
    /* system("pause"); */   /* NOTE: decomment this if you're on windows */
   return EXIT_SUCCESS;
}

~$ ./program

Names found: ATB,Nujabes,Bonobo,Aphex