Thread: problems with opening a file from a string

I am using linux and i'm haveing a problem with this code. It doesn't even seem to open the file. I also tried useing the gets function but GCC warns me that gets() is dangerous and should not be used.

Code:

#include <stdio.h>
#include <string.h>
#include <ctype.h>
#define MAX_CHAR 40
#define MAX_ARRAY 500
int main(void)
{
        FILE *inp, *outp;
        char instring[MAX_CHAR], outstring[MAX_CHAR];
        double in_array[MAX_ARRAY];
        double current_status;
        int i=0;
        int num;
        printf("please enter a file you would like to use.");
        scanf("%s", instring);
        printf("please enter a file you would like to ouput to");
        scanf("%s", outstring);

        inp = fopen(instring, "r");
        outp = fopen(outstring, "w");
        //read the text file
        while(fscanf(inp, "%lf", current_status) != EOF)
        {
                num += 1;
                in_array[i] = current_status;
        }
        printf("I read %i numbers", num);
        //print the old data to the new text file
        for(i = 0; i<num; i++)
        {
                fprintf(inp, "%f", in_array[i]);
        }
        fclose(inp);
        fclose(outp);

        return 0;
}

Dude, you guys rock. I still can't believe i made that small error with the &. Now i have one problem it opens, it reads, but the printing does not work.

Code:

#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>
#define MAX_CHAR 40
#define MAX_ARRAY 500
int main(void)
{
        FILE *inp, *outp;
        char instring[MAX_CHAR], outstring[MAX_CHAR];
        double in_array[MAX_ARRAY];
        double current_status;
        int i=0;
        int num;
        printf("please enter a file you would like to use.");
        scanf("%s", instring);
        printf("please enter a file you would like to ouput to");
        scanf("%s", outstring);

        inp = fopen(instring, "r");
        outp = fopen(outstring, "w");
        if( inp == NULL || outp == NULL )
        {
                    printf("Error: Could not open one or more required files.");
                        return 0;
        }
        //read the text file
        while(fscanf(inp, "%lf",&current_status) != EOF)
        {
                num += 1;
                in_array[num -1] = current_status;

        }
        printf("I read %i numbers", num);
        //print the old data to the new text file
        for(i = 0; i<num; i++)
        {
                //there hase to be a problem with this printf statement. it doesn't print to the file.
                fprintf(inp, "%f", in_array[i]);
         //added this to see if it really was print the correct number and it is.      
         printf("current number being printed is %f", in_array[i]);
        }
        printf("I printed %i numbers", i);
        fclose(inp);
        fclose(outp);
}

oh my. today is not my dad. i printed to the input file.

in my c class the professor uses the terms call by reference and call by value. I can not find these in the book. could anyone explain this to me?