Using the outputted values from code

[Jonnyfurze]

Hello there. I'm writing a program and I need to export values created from my code into Microsoft Excel. Here is my code:

int main()
{ 
      int i,j, zed;
      float x[1000],y[1000], u=0.25, m=0.5;
      double z[1000], w[1000], a[1000], b[1000];

      for(i=0;i<1000;i++)
         {

              x[i] = 2*((float)rand()/(float)RAND_MAX)-1;
              y[i] = 2*((float)rand()/(float)RAND_MAX)-1; 
              a[i]= pow(x[i],2);
              b[i]= pow(y[i],2);
             w[i] = (a[i]+b[i]);

         }
     j=0;
     for(i=0;i<1000;i++)

     {

         if(w[i]<1){(z[j]=((u*x[i])*(sqrt((-1*2)*(log(w[i])/(w[i])))))+m);j++;}

     }
     zed = j;
     for(j=0;j<zed;j++)
       {
           printf("%f\t",z[j]);
       }

     return 0;
}

So I need all of the 'z[j]' array values to be exported into Excel. I've read about CSV files and fprintf but I couldn't find any good examples of their uses. Any help would be much appreciated.

[anduril462]

Your code is hard to read:

• Include your header files so I don't have to screw around getting your code to compile.
• Your indentation is crap. Read these, pick one of the top 3 styles from the Wikipedia article: Indentation - cpWiki and Indent style - Wikipedia, the free encyclopedia.
• You need white space around your operators.
• Don't put giant, ugly if statements on one line with their subordinate clauses. The if () part goes on one line, the statements inside the if go on their own lines.
• Don't use magic numbers. #define NUM_ELEMENTS 1000, and replace all the uses of 1000 with NUM_ELEMENTS.

On this very site, we have a great FAQ article on working with files: Cprogramming.com FAQ > Work with files (C), and we have a tutorial as well: C File I/O Tutorial - Cprogramming.com. Wikipedia has some good info on CSV files: Comma-separated values - Wikipedia, the free encyclopedia. You need to tell us what exactly you don't get about fprintf and CSV files.

[King Mir]

CSV files are just comma separated values. Newline indicates the next row, comma indicates the next column. So to create 1D column, write each element to a file, with one element per line.

As for fprintf, there are tutorials and any book will explain how to use it. You should get a good book.

Also, use descriptive variable names.

[Jonnyfurze]

Thankyou so much for your help, I went out today and got programming in C for dummies, was very helpful. I was able to write the array Z[j] to a txt file. However when I open it up in excel it comes up with a Text Import Wizard where I have to sort out columns to import the data. Is there a way to write the code so I don't have to go through this text import wizard?
Here is my new code:

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define NUM_ELEMENTS 1000
int main()
{
    int i,j, zed;
    float x[ NUM_ELEMENTS],y[ NUM_ELEMENTS], u=0.25, m=0.5;
    double z[ NUM_ELEMENTS], w[ NUM_ELEMENTS], a[ NUM_ELEMENTS], b[ NUM_ELEMENTS];


    for(i=0;i<1000;i++)
        {

        x[i] = 2*((float)rand()/(float)RAND_MAX)-1;
        y[i] = 2*((float)rand()/(float)RAND_MAX)-1;
        a[i]= pow(x[i],2);
        b[i]= pow(y[i],2);
        w[i] = (a[i]+b[i]);

        }
    j=0;
    for(i=0;i<1000;i++)

        {

        if(w[i]<1)
            {(z[j]=((u*x[i])
                    *(sqrt((-1*2)
                           *(log(w[i])
                                /(w[i])))))+m);
                                        j++;
            }



        }
        zed = j;
        for(j=0;j<zed;j++)
            {
            printf("%f\t",z[j]);
            }
FILE *myfile;

    myfile = fopen("program.txt","w");
    if(!myfile)
    {
        puts("some kind of file error!");
        return(1);
    }
    zed = j;
        for(j=0;j<zed;j++)
            {
            fprintf(myfile, "%3d %f\n",j,z[j]);
            }
    fclose(myfile);

    return 0;
}

[anduril462]

Thankyou so much for your help

You're welcome.

Is there a way to write the code so I don't have to go through this text import wizard?

Nope. Excel does that whenever you import a delimited file. It forces you to say whether there's a header row, whether the file is comma delimited, tab delimited, etc. It has to know how to parse it, and you have to tell it. There's nothing you can do in your code to avoid that.

Here is my new code:

Much better! The only thing left I see to fix is your for loops. You need to use NUM_ELEMENTS in your for loops too. The idea of constants is that you use the name everywhere, and if you have to change the value, you only have to do it in one place, not 3.

     for(i=0;i<NUM_ELEMENTS;i++)

[KCfromNC]

If you call the output something like foo.csv and open it with excel, it should open without any prompts. I do it all the time. You can ether drag and drop the file or do "start foo.csv" from the command line or just do a file->open from excel and it opens as if it were any other spreadsheet. Be careful about editing and saving this file, though, since CSV can't handle a lot of the formatting you can do to a normal file. Use save as to save it as an xlsx/xlsb/xlsm/xls/whatever format if you want to modify and save the file for later.