Array of Struct failing at the last index

Question

#include <stdio.h>
#include <string.h>
#include <string.h>
struct student
{
     int id;
     char name[30];
     float percentage;
};

int main()
{
     int i;
     struct student record[2];

     // 1st student's record
     record[0].id=1;
     strcpy(record[0].name, "Raju");
     record[0].percentage = 86.5;

     // 2nd student's record
     record[1].id=2;
     strcpy(record[1].name, "Surendren");
     record[1].percentage = 90.5;

     // 3rd student's record
     record[2].id=3;

     //strcpy(record[2].name, "Thiyagu");//--->Bug in this line

     //record[2].percentage = 81.5;//--->Bug in this line


     for(i=0; i<3; i++)
     {
         printf("     Records of STUDENT : %d \n", i+1);
         printf(" Id is: %d \n", record[i].id);
         printf(" Name is: %s \n", record[i].name);
         printf(" Percentage is: %f\n\n",record[i].percentage);
     }
     return 0;
}

I am having a difficult time debugging this code. For some reason the lines that I marked(-->) breaks the code. Right now this line and the one underneath are commented out because the code doesn't execute with them. I have a feeling it has to do something with the null terminator.

You are putting three items into an array of two items (i.e 0, 1, 2). Computers start counting at zero — Ed Heal, Mar 12 '15 at 22:49
I know that they start at 0. The array size is record[2] which means it has 0,1, 2! — bluestar99, Mar 12 '15 at 22:51
`struct student record[2];` You know this creates array of size 2, don't you? Its capacity is 2 structures, not the indexing stops at 2. — zubergu, Mar 12 '15 at 22:51
C gives you enough rope to hang most of the town you live in — Ed Heal, Mar 12 '15 at 22:53
@RT89 yes you can even do `record[200000];` with a undefined behavior, something compiles doesn't mean its correct — P0W, Mar 12 '15 at 22:54
Guys I am new at C. Sorry this is a newly mistake, and thanks for explaining — bluestar99, Mar 12 '15 at 22:56

score 6 · Answer 1 · edited May 23 '17 at 12:22

6

struct student record[2]; means that the array has 2 entries. The valid indices are 0 and 1.

Trying to access record[2] causes undefined behaviour.

edited May 23 '17 at 12:22

Community

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answered Mar 12 '15 at 22:52

M.M

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I thought record[2] worked as 0,1,2. I change it to 3 and works fine. Thanks – bluestar99 Mar 12 '15 at 22:54

Array of Struct failing at the last index

1 Answers1