Cant sort array of struct

Question

I have an array of struct,that I read from the text file.I wrote a sort function,that has to sort this array by the name field in alphabet order(A-Z),but it doesnt work,i dont know what to do,plz,can you tell me my mistake(code compiles,but it doesnt sort anything).

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

int my_compare(const void*,const void*);
typedef struct {
    char name[100];
    char surname[100];
    char sname[100];
    char posada[100];
    char buff[100];
    int staz;
    char buff2[100];
    int oklad;
} test;
        ;
int main()
{
    test mass[7];
    /*struct test{
        char name[100];
        char surname[100];
        char sname[100];
        char posada[100];
        char buff[100];
        int staz;
        char buff2[100];
        int oklad;
    }mass[8];
    */
    FILE *fo;
    if((fo=fopen("C:\\Users\\andyb\\Desktop\\test2.txt","r"))==NULL)
        printf("error");
    for(int i=0;i<7;i++)
    {
        fgets(mass[i].name,50,fo);
        fgets(mass[i].surname,50,fo);
        fgets(mass[i].sname,50,fo);
        fgets(mass[i].posada,50,fo);
        fgets(mass[i].buff,50,fo);
        mass[i].staz=atoi(mass[i].buff);
        fgets(mass[i].buff2,50,fo);
        mass[i].oklad=atoi(mass[i].buff2);
    }
    fclose(fo);
    for(int i=0;i<7;i++)
    {
        printf("%s%s%s%s%d\n%d\n",mass[i].name,mass[i].surname,mass[i].sname,mass[i].posada,mass[i].staz,mass[i].oklad);
    }
    qsort( mass, sizeof(mass)/sizeof(mass[0]), sizeof(mass[0]), my_compare );
    for(int i=0;i<7;i++)
    {
        printf("%s%s%s%s%d\n%d\n",mass[i].name,mass[i].surname,mass[i].sname,mass[i].posada,mass[i].staz,mass[i].oklad);
    }

    return 0;
}

int my_compare(const void *a,const void *b)
{
    const test *pa = (const test *)a;
    const test *pb = (const test *)b;

    return strcmp( pa->name, pb->name );
}

It does not sort -> It does not do something at all? How is the text file formatted? — arc_lupus
– arc_lupus, Commented Oct 6, 2016 at 5:50
Is there any particular reason why you are not initializing mass[0] ? — selbie
– selbie, Commented Oct 6, 2016 at 5:52
Because you aren't initializing mass[0], but you are definitely trying to sort with it. :) — selbie
– selbie, Commented Oct 6, 2016 at 5:53
Your last loop still iterates out of bounds. Do you mind show us a sample of your input file too? — Bob__
– Bob__, Commented Oct 6, 2016 at 6:06

selbie · Accepted Answer · 2016-10-06 05:56:11Z

3

Your for loops look incorrect:

Instead of this:

for(int i=1;i<8;i++)

You should be saying this:

for(int i=0;i<8;i++)

Otherwise, mass[0] is going to contain garbage data and all sorts of undefined behavior will occur when you try to sort against it.

answered Oct 6, 2016 at 5:56

selbie

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5 Comments

andybelous Over a year ago

ive already fixed that,check my question,still doesnt work :(

selbie Over a year ago

Then post your input file (test2.txt) as well and I'll take a deeper look.

selbie Over a year ago

Also, you still have a for-loop bug in your corrected question.

andybelous Over a year ago

where is it?I use for(int i=0;i<7;i++),now i store my data in mass[0]

andybelous Over a year ago

@kaylum if that is true I would not be able to read my array from file,but it reads it and prints everything correctly,but it still cant sort

Ruhul · Accepted Answer · 2016-10-06 06:40:57Z

0

    for (i = 1; i < n; i++)
          for (j = 0; j < n - i; j++) 
          {
             if (strcmp(mass[j].name, mass[j + 1].name) > 0) 
             {
                temp = mass[j];
                mass[j] = mass[j + 1];
                mass[j + 1] = temp;
             }
          }

answered Oct 6, 2016 at 6:40

Ruhul

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