Getting column data from file stream in C - c

Question

I have a file which is written with a column of data (For example, "250\n 249\n...". Actually, there are 250 rows data with at most 15 digits in a row). I wish to get data from the different files and average them. However, I have no idea how could I get such a large amount of data with single column. I tried the following:
char str[80];\newline
FILE * abc;
abc=fopen("bromo.dat", "r");
fgets(str, 80, msd);
atof(str);
What I got was only the data from the first row. How could get the rest of the data?

Answer 1

You can use strtok to split the number in each line by space character. Then use the atof funcition as you used in your code to convert string to float number.
You should use 2D array to store all numbers in the file, and use another array to store the number in each line:
float number[250][15]; // maximum 250 line with at most 15 digits in each line
int number_each_line[250] = {0}; // the number of digits in each line
The complete program for test:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main() {
char str[80];
float number[250][15];
int number_each_line[250] = {0};
FILE * fp;
fp =fopen("bromo.dat", "r");
if (!fp) {
return -1;
}
int i = 0;
while(fgets(str, 80, fp) && i < 250) {
int j = 0;
char *token = strtok(str, " ");
while(token != NULL) {
number[i][j] = atof(token);
j++;
token = strtok(NULL, " ");
}
number_each_line[i] = j;
i++;
}
// print first 10 lines in file
for(int k = 0; k < 10; k++) {
for(int j = 0; j < number_each_line[k]; j++) {
printf("%f ", number[k][j]);
}
printf("\n");
}
fclose(fp);
}
The output of test:
bromo.dat:
1.2 1 4 5
2.1 2 6 7 8
3.5 3 2 3 5.3
2.1 4 6 7 8
2.1 5 6 7 8
2.1 6 6 7 8
2.1 8 6 7 8
2.1 9 6 7 8
2.1 10 6 7 8
./test
1.200000 1.000000 4.000000 5.000000
2.100000 2.000000 6.000000 7.000000 8.000000
3.500000 3.000000 2.000000 3.000000 5.300000
2.100000 4.000000 6.000000 7.000000 8.000000
2.100000 5.000000 6.000000 7.000000 8.000000
2.100000 6.000000 6.000000 7.000000 8.000000
2.100000 8.000000 6.000000 7.000000 8.000000
2.100000 9.000000 6.000000 7.000000 8.000000
2.100000 10.000000 6.000000 7.000000 8.000000