Reading double from a file with system call read - c

Question

double a[5];
for(int i = 0; i < 5; ++i){
read(fd, &a[i], sizeof(double));
}
When I print the content of the array, it shows me only zeros. How can I read double numbers from a text file without using fscanf?
File.txt
2.00 5.11 6.90 3.4 8.7
If I read char by char until the end of line, everything is fine.

Answer 1

As suggested by others if you don't want to use fscanf() then probably you should read all data from file using read() and store into char buffer and parse upto whitespace and then use strtod() to convert resultant string into double.
Here is the helping solution not complete one
int main() {
int fd = open("input.txt",O_RDWR | 0664);
if(fd == -1) {
perror("open");
return 0;
}
/* first find the size of file */
int size = lseek(fd,0,2);
printf("size of file : %d \n",size);
lseek(fd,0,0);/* again start reading from beginning */
/* take buffer equal to size of file */
char *buf = malloc(size * sizeof(char) + 1);
/* read all at a time using read()*/
read(fd,buf,size);
buf[size] = '\0';
printf("%s\n",buf);
/* now parse using strtod() */
double res;
char new_buf[64]; /* to store each double number read from fil
e */
for(int iter = 0,inner_iter = 0;buf[iter] != '\0' ;iter++ ) {
if(buf[inner_iter]!=' ' ) {
new_buf[inner_iter++] = buf[iter];
continue;
}
else {
new_buf[inner_iter] = '\0';
res = strtod(new_buf,NULL);
printf("%lf\n",res);
inner_iter = 0; /* make this variable 0 again */
}
}
free(buf);
close(fd);
return 0;
}