Reading text file into an array in C

Question

I want to parse a .txt file into a 1D array in C. I'm using the fgets function to read the contents of the file into the array("waveform" as the array into which the file contents are to be stored - defined as a "char"). The saved values need to be saved into a new array as integer values. I am not sure where I am going wrong. P.S: I am new to programming in C, please bear with me :) Please ignore the indexing issues, done due to pasting

int main(){
    int a, win[10];

    FILE *filename = fopen("testFile.txt","r");
    char waveform[10];

    if (filename == NULL)
    {
        printf("Error opening file.\n");
        exit(8);
    }

    for(int i =0;1;i++){
        if(fgets(waveform[i], 10, filename) == NULL);
        break;

                if(i < 10)
            {
           a = atoi(waveform[i]);
           win[i] = a;
            }
         }

    fclose(filename);

    return 0; 
}

Compiler errors - image embedded

Data in testFile.txt: 1 to 10 in a row vector.

Answer 1

You are on the right track. Here is my contribution on the topic:

1. Open the file (fopen)
2. Count number of lines (getc and rewind)
3. Read all lines into array (getline)
4. Free memory and close file (free and fclose)

Code example:

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

int main(int argc, char *argv[])
{

  // Open File
  const char fname[] = "testFile.txt";

  FILE *fp = fopen(fname, "r");

  if( !fp )
    goto error_open_file;
  printf("Opened file: %s\n", fname); 

  // Count Lines
  char cr;
  size_t lines = 0;

  while( cr != EOF ) {
    if ( cr == '\n' ) {
      lines++;
    }
    cr = getc(fp);
  }
  printf("Number of lines: %ld\n", lines); 
  rewind(fp);

  // Read data
  {// 'goto' + data[lines] causes error, introduce block as a workaround
    char *data[lines];
    size_t n;

    for (size_t i = 0; i < lines; i++) {
      data[i] = NULL;
      size_t n = 0;

      getline(&data[i], &n, fp);

      if ( ferror( fp ) )
        goto error_read_file;

    }

    for (size_t i = 0; i < lines; i++) {
      printf("%s", data[i]);
      free(data[i]);
    }
  }

  // Close File
  fclose(fp);

  return 0;

error_read_file:
  perror("fopen ");
  return 1;

error_open_file:
  perror("getline ");
  return 2;

}