How can I parse data from a file

This is a discussion on How can I parse data from a file within the C Programming forums, part of the General Programming Boards category; hi: Here are some dataset: ================= dog;This is a dog;11 cat;no cat here;4 !EMPTY!;blabla;-1 blablabla Here is the function to ...

  1. #1
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    How can I parse data from a file

    hi:
    Here are some dataset:
    =================
    dog;This is a dog;11
    cat;no cat here;4
    !EMPTY!;blabla;-1
    blablabla

    Here is the function to read data:
    =======================
    Code:
        while (fscanf(inputFp, "%s;%s;%d", Pattern.string, Text.string,    &expectedIndex) != EOF )  {
             ...........
        }
    The problem is that how can I read "This is a dog" into Text.string.
    Should I use fscanf, or I can use something simpler?

    Appreciate for help.

    @figo2476

  2. #2
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    How about the strtok() function?
    http://www.cppreference.com/stdstring/strtok.html

  3. #3
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    I am not sure how it works with fscanf, because the length of the string which is to be read, is not specified.

    One way is use fgetc(file pointer) and read each character, and when you find a ';', look for first 4 characters. if the first 4 characters string is "This", then read the rest of the characters until you find a ';' again.
    Last edited by spveer; 08-18-2005 at 03:38 AM.

  4. #4
    Just Lurking Dave_Sinkula's Avatar
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    7. It is easier to write an incorrect program than understand a correct one.
    40. There are two ways to write error-free programs; only the third one works.*

  5. #5
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    reply

    I tried this and I found something intresting:

    Here is my code:
    ---------------------
    Code:
    int main(int argc, char *argv[])
    {
    
      FILE *inputFp;
      FILE *outputFp;
    	
      int shift = 0;
      STRING Pattern;
      STRING Text;
      char buffer[BUFFER_LEN];
      char lenArray[100];
      char field[200];
      char *ptr = NULL;
      char *patternTmp, *textTmp, *expect; 
      int len;
      int n;
    
      inputFp = fopen(INPUT, "r");
      if (inputFp == NULL) {
    	printf("Can't open input file: TestCases.in");
    	exit(0);
      }
      
      outputFp = fopen(OUTPUT, "w");
      if (outputFp == NULL) {
    	printf("Can't open output file: TestResults.out");
    	exit(0);
      }
    
      /* Read the input file */
      while (fgets(buffer, BUFFER_LEN, inputFp)) {
    	ptr = strtok(buffer, "\n"); 
    	while (sscanf(ptr, "%199[^;]%*c%n", field, &n) == 1) {
    		ptr += n;
    		printf("field = %s\n", field);
    	}
    
      }
    
      fclose(inputFp);
      fclose(outputFp);
    
    
    My input file
    ----------------
    dog;This is a dog;11
    cat;no cat here;4
    EMPTY;blabla;-1
    EMPTY;EMPTY;1
    dog;This dog;11
    
    
    My output 
    -------------
    field = dog
    field = This is a dog
    field = 11
    field = cat
    field = no cat here
    field = 4
    field = EMPTY
    field = blabla
    field = -1
    field =                       /* I am  not sure this */
    field = EMPTY
    field = EMPTY
    field = 1
    field = dog
    field = This dog
    field = 11
    
    }

  6. #6
    Just Lurking Dave_Sinkula's Avatar
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    Thanks for finding that. Perhaps this would work better.
    Code:
    #include <stdio.h>
    #include <string.h>
    
    int main(void)
    {
       static const char filename[] = "file.txt";
       FILE *file = fopen(filename, "r");
       if ( file != NULL )
       {
          char line [ BUFSIZ ];
          while ( fgets(line, sizeof line, file) != NULL )
          {
             int n;
             char field [ BUFSIZ / 2 ], *ptr = strtok(line, "\n");
             printf("line  = \"%s\"\n", line);
             while ( sscanf(ptr, "%199[^;]%n", field, &n) == 1 )
             {
                printf("field = %s\n", field);
                ptr += n;
                if ( *ptr != ';' )
                {
                   break;
                }
                ++ptr;
             }
             putchar('\n');
          }
          fclose(file);
       }
       else
       {
          perror(filename);
       }
       return 0;
    }
    
    /* file.txt
    dog;This is a dog;11
    cat;no cat here;4
    EMPTY;blabla;-1
    EMPTY;EMPTY;1
    dog;This dog;11
    */
    
    /* my output
    line  = "dog;This is a dog;11"
    field = dog
    field = This is a dog
    field = 11
    
    line  = "cat;no cat here;4"
    field = cat
    field = no cat here
    field = 4
    
    line  = "EMPTY;blabla;-1"
    field = EMPTY
    field = blabla
    field = -1
    
    line  = "EMPTY;EMPTY;1"
    field = EMPTY
    field = EMPTY
    field = 1
    
    line  = "dog;This dog;11"
    field = dog
    field = This dog
    field = 11
    */
    7. It is easier to write an incorrect program than understand a correct one.
    40. There are two ways to write error-free programs; only the third one works.*

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