tsaiwn@magpie % cat -n readin.c
     1  //readin.c  --- fopen/fgets --- copyLeft by tsaiwn@csie.nctu.edu.tw
     2  #include <stdio.h>
     3  #include <stdlib.h>
     4  char FNAME[ ] = "abc.txt";
     5  int main( ) {
     6     FILE* fp;
     7     static char buf[99];
     8     double ans, x;
     9     int n;
    10     fp = fopen(FNAME, "rt");    // open for read, text file
    11     if(fp == 0) {
    12         fprintf(stderr, "open file %s ", FNAME);
    13         perror("Error ");
    14         return 38;
    15     }
    16     ans = n = 0;
    17     fgets(buf, sizeof(buf), fp);
    18     while( !feof(fp) ) {
    19         ++n;  x = atof(buf);
    20         ans += x;
    21         printf("%f ", x);
    22         fgets(buf, sizeof(buf), fp);
    23     }
    24     printf("\nTotal %d items. Sum = %f\n", n, ans);
    25     return 0;
    26  }
tsaiwn@magpie % cat abc.txt
1.2
2.3
3.4
tsaiwn@magpie % gcc readin.c
tsaiwn@magpie % ./a.out
1.200000 2.300000 3.400000 
Total 3 items. Sum = 6.900000

tsaiwn@magpie % cat -n readin.cpp
     1	//readin.cpp  --- cin.getline --- copyLeft by tsaiwn@csie.nctu.edu.tw
     2	//g++ readin.cpp -Wno-deprecated ;  ./a.out
     3	#include <iostream.h>
     4	#include <fstream.h>
     5	#include <stdlib.h>
     6	char FNAME[ ] = "abc.txt";
     7	int main( ) {
     8	   fstream in;     // required <fstream.h>
     9	   static char buf[99];
    10	   double ans, x;
    11	   int n;
    12	   in.open(FNAME, ios::in); // open for read, text file
    13	   if(in.fail( ) ) {
    14	       cerr << " Error open file " << FNAME << endl;
    15	       perror("Error ");
    16	       return 38;
    17	   }
    18	   ans = n = 0;
    19	   in.getline(buf, sizeof(buf) );    // read first record
    20	   while( !in.eof() ) {
    21	       ++n;  x = atof(buf);     // need <stdlib.h>
    22	       ans += x;
    23	       cout << x << " ";
    24	       in.getline(buf, sizeof(buf) );
    25	   }
    26	   cout << "\nTotal "<< n << " items. Sum = ";
    27	   cout << ans << endl;
    28	   return 0;
    29	}
tsaiwn@magpie % g++ -Wno-deprecated readin.cpp
tsaiwn@magpie % ./a.out
1.2 2.3 3.4
Total 3 items. Sum = 6.9

tsaiwn@magpie % exit
exit