Reading numbers from a text file into an array in C

Question

I m a programming noob so please bear with me   I m trying to read numbers from a text file into an array  The text file   somenumbers txt  simply holds 16 numbers as so  5623125698541159     include  lt stdio h gt  main          FILE  myFile      myFile   fopen  somenumbers txt    r           read file into array     int numberArray 16       int i       for  i   0  i  lt  16  i                  fscanf myFile    d    amp numberArray i               for  i   0  i  lt  16  i                  printf  Number is   d n n   numberArray i                The program doesn t work  It compiles but outputs   Number is  -104204697  Number is  0  Number is  4200704  Number is  2686672  Number is  2686728  Number is  2686916  Number is  2004716757  Number is  1321049414  Number is  -2  Number is  2004619618  Number is  2004966340  Number is  4200704  Number is  2686868  Number is  4200798  Number is  4200704  Number is  8727656  Process returned 20  0x14    execution time   0 118 s Press any key to continue

User · Accepted Answer

change to  fscanf myFile    1d    amp numberArray i

User · Answer

Loop with  c to read the stream character by character instead of  d

User · Answer

5623125698541159 is treated as a single number  out of range of int on most architecture   You need to write numbers in your file as    5 6 2 3 1 2 5  6 9 8 5 4 1 1 5 9     for 16 numbers     If your file has input     5 6 2 3 1 2 5 6 9 8 5 4 1 1 5 9    then change  d specifier in your fscanf to  d        fscanf myFile    d     amp numberArray i         Here is your full code after few modifications      include  lt stdio h gt   include  lt stdlib h gt   int main         FILE  myFile      myFile   fopen  somenumbers txt    r           read file into array     int numberArray 16       int i       if  myFile    NULL           printf  Error Reading File n            exit  0              for  i   0  i  lt  16  i             fscanf myFile    d     amp numberArray i                for  i   0  i  lt  16  i             printf  Number is   d n n   numberArray i               fclose myFile        return 0

User · Answer

There are two problems in your code    the return value of scanf must be checked the  d conversion does not take overflows into account  blindly applying  10   newdigit for each consecutive numeric character    The first value you got  -104204697  is equals to 5623125698541159 modulo 2 32  it is thus the result of an overflow  if int where 64 bits wide  no overflow would happen   The next values are uninitialized  garbage from the stack  and thus unpredictable   The code you need could be  similar to the answer of BLUEPIXY above  with the illustration how to check the return value of scanf  the number of items successfully matched     include  lt stdio h gt   int main int argc  char  argv          int i  j      short unsigned digitArray 16       i   0      while           i    sizeof digitArray    sizeof digitArray 0         amp  amp  1    scanf   1hu   digitArray   i                  i              for  j   0  j    i  j              printf   hu n   digitArray j              return 0

User · Answer

for  i   0  i  lt  16  i          fscanf myFile    d    amp numberArray i        This is attempting to read the whole string   5623125698541159  into  amp numArray 0    You need spaces between the numbers   5 6 2 3

[c] Reading numbers from a text file into an array in C

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