Thread: scanning strings and integers from a file

im not too sure what parallel arrays are lol but whatever works is good for me. our professor has never really taught an introductory programming class so every assignment has been quite a challenge and he hasnt really explained how things work or how to tackle problems

just a few questions:

1. if i were to create an array to scan in the names of each player, would i declare:

char player_name[999][20]

since there is a possibility of up to 999 players with the first and last name both being at most 10 characters long?

2. i somewhat know how to use 2D arrays for integers but will the fact theres rows of characters affect how the arrays for int work?

for example, since there are four columns of integer data, could i just decalre:

int stats[3][999];

and run loops so that i can scan stats[0][1-999], stats[1][1-999] etc

without having to worry about the rest of the stuff in the file?

Parallel arrays is simply exploiting the fact that the data and names for any one player, are all in the same row - just in different arrays. Thus, the arrays are used "in parallel".

In my previous post, Adam and his data, are all in the 0 row.

My rule of thumb is it's easier to use a struct for any more than three arrays to be used in parallel. Just makes it easier. Neither is beyond understanding, or esoteric, in any sense.

Yes, arrays that need to have rows and columns in them (like here), would be 2D arrays.

No, names would need more than 20 char's - there is an end of string char: '\0' that is unseen, but must go on the end of all strings - otherwise they're just a bunch of char's, and not elevated to string status, in C. Handling them becomes tedious.

Would there also be a space between the names? Need another char space for that, also.

there would be spaces between first and last name, however, each new person is on a different line eg:

John Smith
Jane Doe
John Doe
etc

would be one column. right now im trying to scan just the first names in just so i know the fscanf is working and im getting the right data:

Code:

  int i = 0, index[i];
  char first_name[999][22];

  while(fscanf(data_file, "%s", first_name[i][22]) != EOF) {
    fscanf(data_file, "%s", first_name[i][22]);
    i = i + 1;
    index[i] = i;
  }

  for (i = 1; i < index[i]; i++) {
    printf("%s, ", first_name[i]);
  }

this little snippet will compile fine but when i execute it, i get a segemntation fault

im not sure what im doing wrong, although, its probably my terrible syntax lol

hmm, i gave it a shot but i just get segmentation faults. i also tried playing around with the loop and the size of the array just to see where the program was trying to call on something it couldnt but no dice

why does my professor hate us so much

Did you change the data in the file, so it was just first names?

You can't just ask the computer program to scan for one thing, and not give it code to handle the rest of the data - it's all read in SEQUENCE.

Try it with a data file of just a few first names, in a different data file, and change the name of the file your program is opening.

Alex
Henrik
Jonathan
Anze
Jarome
Patrick
Brad
Teemu
Sidney

oooooooh i see!

now if i i had a data file like our TA's are going to use with mutliple columns of data, how exactly would i make the scan work around this?

sorry for asking so many questions, we reeeeeeeally werent taught anything about dealing with these kinds of problems so im at a complete loss right now. i definitely want to keep taking classes for this in school but this is driving me mental lol

Originally Posted by GaelanM

Hello, Im new to programming and Im taking an introductory programming course at my university. It is our last assignment for the semester and it is giving me quite a bit of trouble and I was wondering if anyone could help me out.

Basically, I am given a file of an unspecified number of hockey players with all their stats and I need to scan the file for all the names, info etc then calculate their points-per-game and print it back so its sorted from highest ppg to lowest ppg.

The file looks something like:

Players Team pos GP G A P
Daniel Sedin VAN L 73 38 55 93
Steven Stamkos TBL C 72 43 43 86
Henrik Sedin VAN C 73 18 68 86
Martin StLouis TBL R 72 26 59 85
Corey Perry ANA R 72 39 40 79
Alex Ovechkin WSH L 73 29 48 77
Henrik Zetterberg DET L 73 21 52 73
Jonathan Toews CHI C 70 30 42 72
Anze Kopitar LAK C 73 25 47 72
Jarome Iginla CGY R 75 33 38 71
Patrick Sharp CHI L 71 34 34 68
Brad Richards DAL C 62 25 42 67
Teemu Selanne ANA R 63 22 45 67
Sidney Crosby PIT C 41 32 34 66

the problem I am having is I dont't really know how to tackle scanning both strings and integers at the same time into multiple arrays..

Well, in deference to Adak's programming skills...

I wouldn't do that with multiple arrays. I'd be prone to do it with structs and either a single array or a linked list.

Code:

typedef struct t_scores
  { char First[21];
     char Last[21];
     char Team[4];
     char Position;
     int  Games;
     int Goals;
     int Assists;
     int Penalties; 
     t_scores *pNext; }  // for linked list
   Scores, *pScores;

// one record
pScores Player = malloc(sizeof(Scores));

// to read the data
fscanf(" %20s %20s %3s %c %d %d %d %d",
                  Player->First, Player->Last, Player->Team, Player->Position
                  Player->Games, Player->Goals, Player->Assists,Player->Penalties);

The loops, list format (array, linked list, etc) would also have to be worked out but once you have this basic data structure working you will have a list of players each stored in their own data struct.

Parallel arrays can work... but, really, isn't this a lot simpler?

I would use fgets to get a whole line of data into a c-string I use char array size of 256 to be extra safe.
fgets - C++ Reference
And, then use sscanf to get the fields from the c-string

There is many other ways to do it.

Tim S.

hmm i never thought of using fget, and im not to familiar with struc to use it; this is the first ive ever heard of them.

i dont know if it'll matter, but i want to get all of the information into arrays just because itll be a bit easier for me to understand whats going on and on top of that, i will have to sort all the data and print it back.. which i have no idea if doing anything other than arrays will make it any more difficult/easy

Originally Posted by GaelanM

hmm i never thought of using fget, and im not to familiar with struc to use it; this is the first ive ever heard of them.

Well... look ahead in your textbooks... They're there... and they will be a LOT easier to work with in this case. (struct == Data Structures)

i dont know if it'll matter, but i want to get all of the information into arrays just because itll be a bit easier for me to understand whats going on and on top of that, i will have to sort all the data and print it back.. which i have no idea if doing anything other than arrays will make it any more difficult/easy

Take my word for it... parallelling 2 arrays is a pain... you're talking about between 4 and 8 of them.

If you are not at the point where structs and linked lists have been covered in your course, your instructor should not have given you this assignment. (No joke...)