strstr char array inside struct array

问题:

I have a struct defined as;

struct player {

    int no, age;

    char name[20];  

} players[10];

Array is filled from file. What I try to do is, take input from user, add input to char array, send it to search(char lookup[]) function and strstr name field in a loop.

EDİT: Sorry I corrected the order. I'm trying to strstr in a loop.

char *p = strstr(players[x].name, inputFromUser);

but p is always null. How can I do this?

Thanks in advance.

EDIT - Code Added...

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

struct player {

    int no, age;

    char name[20];  

} players[20];

void fillstruct(char *);
void search(char []);

int main(int argc, char *argv[])
{
    int arg;
    int c;        
    int d;           
    int i=0;        

    char a[100];
    char *filename = NULL;

    while((arg=getopt(argc, argv, "f:"))!=-1)
    {
        switch(arg)
        {
            case 'f':
                filename = optarg;
                fillstruct(filename);
                break;
            default:
                break;
        }
    }   
    while((c=fgetc(stdin))!=EOF)
    {
        if(c!=10)
        {
            a[i]=c;
            i++;
        }       
        else
        {
            a[i]='\0';
            search(a);      
            i=0;            
        }       
    }
    return 0;
}

void search(char a[])
{
    int i=0;
    int col;
    int found=0;
    char *p =NULL;
    while((i<20)&&(found==0))
    {
        p = strstr(a, players[i].name);
        if(p)
        {
            col = p-a;
            printf("\nPlayer '%s' found in '%s'.. Found index: %d", a, players[i].name, col);
            found=1;
        }   
        else
        {
            printf("\np=%s a=%s player[%d].name=%s", p, a, i, players[i].name);
        }
        i++;
    }   
}

void fillstruct(char *name)
{
    FILE *fp;
    char line[100];
    int i=0;

    fp = fopen(name, "r");
    if(fp==NULL)
    {   
        exit(1);
    }

    while(fgets(line, 100, fp)!=NULL)
    {
        players[i].no=i;
        strcpy(players[i].name, line);
fprintf(stdout, "\nplayer=%s", players[i].name);
        players[i].age=20;
        i++;
    }   
    fclose(fp); 
}

回答1:

fgets stores the \n and then stops taking input.

So suppose a player name is "user", players[i].name will be equal to "user\n" while a is "user".

So return of strstr is always NULL.

Try this instead:

p = strstr(players[i].name,a);

OR, remove the \n after taking input from file by fgets:

while(fgets(line, 100, fp)!=NULL)
{
    players[i].no=i;
    strcpy(players[i].name, line);
    players[i].name[strlen(players[i].name)-1]='\0'; //add this line
    fprintf(stdout, "\nplayer=%s", players[i].name);
    players[i].age=20;
    i++;
} 

回答2:

Added as answer as suggested by mic_e

Assuming you're trying to search for a player name using the input from a user, you have the arguments of strstr in the reverse order. Also note that strstr is case sensitive.

char *p = strstr(players[x].name, inputFromUser);

回答3:

Like this:

char *p = strstr(players[x].name, inputFromUser);

回答4:

It should work, It's fail if your input is wrong let me expalain in simple

int main()
{
   char *ret;
   char mystr[]="stack";
   char str[]="This is stack over flow string";

   ret = strstr(str, mystr);

   printf("The substring is: %s\n", ret);

   return(0);
}

Output is

The substring is: stack over flow string

That means

This function returns a pointer to the first occurrence in str of any of the entire sequence of characters specified in mystr, or a null pointer if the sequence is not present in str.

It case sensitive function means if try to search like

char mystr[]="Stack";//Note here first char is capital

And you got output like

The substring is: (null)

You can check your input and target string at your side by just printing content of it and verify it's correct or not.

printf("str1:%s str2:%s\n",players[x].name,inputFromUser)
char *p = strstr(players[x].name, inputFromUser);

I hope this clear your doubts.

回答5:

That Should Work.

I think You have the problem with file reading Which fills the data array.

Please make sure that data you filled into structure is Ok.

And strstr returns address of the first Occurrence of the string1 in string2 where, strstr(string2, string1);