Reading a line using scanf() not good?

by

char * fgets ( char * str, int num, FILE * stream ); is safe to use because it avoid buffer overflow problem, it scans only num-1 number of char.

Reads characters from stream and stores them as a C string into str until (num-1) characters have been read or either a newline or the end-of-file is reached, whichever happens first.

here second argument num is Maximum number of characters to be copied into str (including the terminating null-character).

For example suppose in your code a string array capacity is just 5 chars long as below. 

 char str[5];
 fgets (str, 5, fp);  //5 =you have provision to avoid buffer overrun

Using above code, if input from fp is longer then 4 chars, fgets() will read just first 4 chars then appends \0 (, and discard other extra input chars, just stores five char in str[]).

Whereas scanf(" %[^\n]",str); will read until \n not found and if input string is longer then 4 chars scanf() will cause of buffer overflow (as scanf will try to access memory beyond max index 4 in str[]).

More Related Contents:

  1. ‘ ‘, ‘\n’ , scanf() and output screen
  2. What will happen if ‘&’ is not put in a ‘scanf’ statement?
  3. whitespace in the format string (scanf)
  4. Hangman code in C
  5. sscanf Beginner in C
  6. i get Error while trying to compile and Run, [Linker error] undefined reference to `scand’ [closed]
  7. Segmentation fault using scanf() [closed]
  8. What is the effect of trailing white space in a scanf() format string?
  9. How to prevent scanf causing a buffer overflow in C?
  10. Why does scanf() need “%lf” for doubles, when printf() is okay with just “%f”?
  11. C – scanf() vs gets() vs fgets()
  12. What are the rules of automatic stdout buffer flushing in C?
  13. Scanf skips every other while loop in C
  14. Reading in double values with scanf in c
  15. Parsing input with scanf in C
  16. scanf regex – C
  17. What’s the best way to return a random line in a text file using C?
  18. scanf won’t ask for input the second time [duplicate]
  19. Is there a Windows equivalent to fdopen for HANDLEs?
  20. Difference between scanf(“%c”, &c) and scanf(” %c”, &c) [duplicate]
  21. Why does scanf require &?
  22. What is the difference between getch() and getchar()?
  23. printf not printing to screen
  24. Reading numbers from a text file into an array in C
  25. Dynamic String Input – using scanf(“%as”)
  26. How to skip a line when fscanning a text file?
  27. Why does scanf() need & operator (address-of) in some cases, and not others? [duplicate]
  28. How to use sscanf correctly and safely
  29. How do the puts and gets functions work?
  30. Difference between scanf() and fgets()

Leave a Comment