Thread: Altering / Recieving Information from text file question

Just to give some background so my question has some context...

I'm reading in a text file containing the following :

Name: John Smith
Major: EE
GPA: 3.85
Name: Jlsd
Major: CS
GPA: 2.75

And I need to print out to the console this :

Name: GPA : Major:
John Smith 3.85 EE
Jlsd Sdfjkl 2.75 CS

I'm not asking anyone to solve this , but could I get a nudge in the right direction ? Its pretty frustrating

I know my train of thought right now is to get each individual line into an array element starting after the 'Name , GPA , and Major ' but I'm not exactly sure how to do that .

Also , how exactly does a char array work? Does one element essentially hold a "string" or just one character of a string?

example : exampleArray[0] = 'John Smith' ; is that valid and what would it hold? A 'J' or the full name?

while( ( ch = fgetc(ptr)) != EOF )
printf("%c",ch);

I understand this prints out the whole file , but I'm not too sure how to alter this or how exactly to manipulate the gets() to only print or store stuff into another array.

Thanks for your help! Any tips are welcome ! Keep in mind I'm a beginner programmer so go easy !

The common method to process input is to use fgets() and sscanf() to parse the data. You will also want to lookup using structures
as that is definitely what you would want to use here.

As far as your question, a character array holds a single string, example:
char array[20] = "John Smith";
Creates an array of size 20 and initializes it with the string "John Smith"

If you wanted to store multiple strings you would need multi-dimensional array or
some other (more versatile) object (such as a linked list). Here you would probably want
to represent each record with a structure, example:

Code:

struct student {
    char name[MAXNAMELEN+1];
    char major[3]; /* 2 char max limit? +1 for trailing \0 */
    float gpa;
};

Read up on the subjects I discussed above and you will be able to implement what you want.

Thanks a ton! I'm giong through the C tutorial tab now and finding it really helpful!

Now , is there anyway to manipulate fgetsc() to get specific words? Or leave out certain words? So far in class we've mainly been working with standard print / scan file methods so I assume we need to use those but they don't seem specific enough for how I need to manipulate what I need from the file.

Originally Posted by hearthledger

Thanks a ton! I'm giong through the C tutorial tab now and finding it really helpful!

Now , is there anyway to manipulate fgetsc() to get specific words? Or leave out certain words? So far in class we've mainly been working with standard print / scan file methods so I assume we need to use those but they don't seem specific enough for how I need to manipulate what I need from the file.

fgets() is indeed easier initially, but then you still need to get your data into usable variables, probably using sscanf() anway. fscanf() works - it's just more of a pain to set up.

If it's anything the user is entering for data, best to use fgets() since it can be tested more thoroughly. scanf(), fscanf() sscanf(), are all for strictly FORMATTED data. They don't deal well with ANY data that is not formatted to their specifications!

I'm not familiar with fgetsc(), but yes, you can get specific words, but that's probably not what you want.

I'll post an example, in a bit.

With this text file:

Code:

Name: Able Anderson
Major: BIO
GPA: 3.4
Name: John Smith
Major: EE
GPA: 3.85
Name: Charles Green 
Major: CS
GPA: 2.75

I'd suggest:

Code:

#include <stdio.h>
#include <string.h>


int main(void) {
   int i;
   char names[3][40], major[3][30];
   char colon[3]={6,7,5}; //offset to the colon in the string of text+2
   char buffer[40];
   float gpa[3];

   FILE *fp=fopen("test.txt","r");
   if(!fp) {
      printf("Error! File did not open.\n");
      return 1;
   }
   i=0;
   while(fgets(buffer, sizeof(buffer), fp)!=NULL) {
      //printf("buffer:%s\n",buffer);
      sscanf(buffer+colon[0], "%[^\n]",names[i]);
      //get major
      fgets(buffer, sizeof(buffer), fp);
      sscanf(buffer+colon[1], "%[^\n]",major[i]);
      //get gpa
      fgets(buffer, sizeof(buffer), fp);
      sscanf(buffer+colon[2], "%f",&gpa[i]);
      printf("%s\n%s\n%.2f\n\n",names[i],major[i],gpa[i]);
      ++i;
   }   
   
   fclose(fp);
   printf("\n");
   return 0;
}

I tried a few other ideas, but they either were more of an intermediate type, or they were too complex or long.