Strange runtime error, fprintf writes more than asked

Question

I have a runtime error which writes more data from an array than its suppose to print ID, AverageMarks and Status:

Declaration & Its Function

char StudentStatus[10][7];

for(x=0;x<10;x++)
{
   fprintf(OutputFile,"%d\t\t%d\t\t\t%s\n",StudentID[x],StudentAvg[x],StudentStatus[x]);
}

But when it prints

100 77 DismissActive
101 85 Active
102 88 Active
103 86 Active
104 85 Active
105 84 Active
106 84 Active
107 82 Active
108 92 Active
109 75 Dismiss

The way the array was filled:

for(x=0;x<NumOfStudent;x++)
{


  if(StudentAvg[x]>80)
  {
     strcpy(StudentStatus[x],"Active");
     printf(". ");
  }
  else
  {
    strcpy(StudentStatus[x],"Dismiss");
    printf(". ");
  }
}

Other statements works fine but the first statement really troubles me. Any suggestion where I code wrongly?

This code is not sufficient to spot the error. How do you set the array? — perreal, Dec 23 '13 at 03:36
Are you certain that `StudentStatus[0]` is not set to `DismissActive`? — Blorgbeard, Dec 23 '13 at 03:37
Looks like a problem in your `StudenStatus[]` array (maybe a string wasn't zero-terminated). — lurker, Dec 23 '13 at 03:37
Check out this question, and see if you can spot your error: http://stackoverflow.com/questions/20694796/no-compiler-error-when-fixed-size-char-array-is-initialized-without-enough-room — Digital Trauma, Dec 23 '13 at 03:38
Post more code related to how the StudentStatus array is filled. — SoulRayder, Dec 23 '13 at 03:38
perreal:Well the code it quite long but ok. Blorgbeard:Yes its DismissActive.. — Mohd Vara, Dec 23 '13 at 03:41

score 6 · Accepted Answer · answered Dec 23 '13 at 03:40

6

To allow for the terminating null, change your array declaration to:

char StudentStatus[10][8];

C strings are null-terminated, so the string "Dismiss" needs at least 8 bytes of storage.

answered Dec 23 '13 at 03:40

Digital Trauma

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Strange runtime error, fprintf writes more than asked

1 Answers1