Thread: Reading a file (one double number in each line)

You need to use the address operator '&'

Code:

fscanf(file1, "%lf", &bb);

You need to ensure that the file has been opened after the fopen.

If "argc should be 5 for correct execution" then wy are you testing it against 2?

Your loop control assumes that there are going to be exactly 99 doubles in the file. What if there are less? You need to test fscanf for a return value of 1. If it returns something else, exit the loop.

These two have already been mentioned:

You need to use "%lf" as the format specifier for a double.

You need to pass the address of bb, not its value. So use &bb.

Originally Posted by nonoob

You need to use the address operator '&'

Code:

fscanf(file1, "%lf", &bb);

Thanks, I updated my code, but there is another problem. Since I assume that the length is 100 in the file. I created a text file which only have 3 double values, but my program repeat the last value for many times (I guest 98 times). How I can solve it? The following is the new code.

Code:

#include <stdio.h>
#include <math.h>
#include <sys/types.h>
#include <sys/stat.h>


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

    int i;
    double bb;

    FILE *file1 = fopen( argv[1], "r" );



    if ( argc !=2 ) /* argc should be 2 for correct execution */
    {
        printf( "Error of input argument number" );
    }



    for (i=1;i<100;i++){
        fscanf(file1, "%lf",&bb);
        printf("%f",bb);
    }
}

Originally Posted by zmarcoz

Thanks, I updated my code, but there is another problem. Since I assume that the length is 100 in the file. I created a text file which only have 3 double values, but my program repeat the last value for many times (I guest 98 times). How I can solve it?

You solve it by more carefully reading the previous responses people gave you. In particular, oogabooga's response in post #9 about checking the return value of fscanf.

Originally Posted by anduril462

You solve it by more carefully reading the previous responses people gave you. In particular, oogabooga's response in post #9 about checking the return value of fscanf.

Good blame. Solved .............