从C中的文本文件读取和解析文本

Question

Question:

I am trying to read each line from a file (.txt file below) while storing its contents in the appropriate variables. The problem occurs when compiling. I am told there is a segmentation fault but am not sure why this occurring.

tester1.txt file(disregard spaces)

1/12/04 Jones, John $31.11

12/22/03 Dickinson, Tony $5.04

12/15/03 Lee, Jerry $21.12

12/19/03 Kahn, Chris $83.15

1/31/04 Bills, Mike $32.00

1/15/04 Lake, Jeff $6.66

Code:

int main() {

      int month, day, year;
      float money;
      char *lastname, *firstname;
      static const char filename[] = "tester1.txt";

      FILE *file = fopen (filename, "r");

      if (file != NULL) {  
        char line [128]; /* or other suitable maximum line size */
        while (fgets(line, sizeof line, file ) != NULL) {

          sscanf(line,"%d/%d/%d %s, %s $%f", &month, &day, &year, lastname,
        firstname, &money);
          printf("%d/%d/%d %s, %s $%.2f\n", month, day, year, lastname,
        firstname, money );
          // printf("valid: %s\n", line);  
          //  fputs ( line, stdout ); /* write the line */
        }
        fclose (file);
      }
      else {
        perror (filename); /* why didn't the file open? */
      }
      return 0;

}

Answer 1

You need to allocate memory for the strings, you can't just declare them as pointers:

char lastname[256], firstname[256];

Also, in the scanf you can specify anything but comma (and space), otherwise the comma is also read as a part of the string:

sscanf(line,"%d/%d/%d %[^, ], %s $%f", &month, &day, &year, 
                lastname, firstname, &money);

Answer 2

First you have allocate memory for the strings, like perreal said. Then you have to change the sscanf

char str_money[100];

sscanf(line,"%d/%d/%d %s%s%s",
       &month, &day, &year, lastname, firstname, str_money);

Because if you scanf %f, you will not get that tidy float number. And scanf %s only stop at space