如何读取 C 中每一行都有数字的文件？

Question

I'm trying to read a file that contains 10 numbers then adding them to an array so I can sort them later on but I'm having trouble reading them in. Not sure why this isn't working for me, can someone explain what is wrong? There's only a number on each lines.

10.05
11.01
9.03

    double nums[10] = {0};
    int count;

    if ((fptr = fopen("filename", "r")) == NULL){
            printf("Error opening file.\n");
    }

    while ((c = getc(fptr)) != EOF){
            if (c != '\n'){
                    nums[count] = (double)c;
                    count = count + 1;
            }
    }
    fclose(fptr);

Answer 1

What is wrong:

• You are storing only one character.
• You are updating count each times on non-newline characters while updating should be on newline characters.
• count is used without being initialized.
• Casting to double is not for this usage.

Possible fix:

int c;
FILE* fptr;

char line[1024]; // add line buffer and size tracking
int lineCount = 0;
double nums[10] = {0};
int count = 0; // initialize count

if ((fptr = fopen("filename", "r")) == NULL){
        printf("Error opening file.\n");
} else { // avoid using NULL to read file

    while ((c = getc(fptr)) != EOF){
            if (c == '\n'){ // update nums on newline character
                    line[lineCount] = '\0'; // don't forget to terminate the string
                    nums[count] = atof(line); // atof() from stdlib.h is useful to convert string to number
                    count = count + 1;
                    lineCount = 0; // start to read next line
            } else { // read line contents
                line[lineCount] = (char)c;
                lineCount = lineCount + 1;
            }
    }
    fclose(fptr);
}

Answer 2

Here I go

#include <stdio.h>
#include <stdlib.h>

int main()
{
   double values[10];
   int count;
   FILE *f = fopen("filename", "r");
   if (f == NULL)| {
      fprintf(stderr, "Some error message");
      return EXIT_FAILURE; // We cannot go any further - file is dead
   }
   // This is basic - you could overcome error problems
   // When able to read (including white space) we carry on until the array is full
   //  This is an area for improvement - error checking etc. 
   for (count = 0;  count < 10 && fscanf(f, " %lf", &values[count]) != 1; count ++);
   fclose(f);
   return EXIT_SUCCESS;
}