c - reading a specific column in data file
<p>So I created a data file like so:</p>

<pre><code>for(size_t n = ...;...;...){
    //do some stuff
    double mean_value = ...
    double min_value = ...
    double max_value = ...

    FILE *fp = fopen(OUTPUT_FILE,"a+");
    fprintf(fp,"%d %lf %lf %lf\n",n,mean_value, min_value, max_value);
    fclose(fp);
}
</code></pre>

<p>And now i want to read the <code>mean_value</code>s that I've written...</p>

<pre><code>FILE *fp = fopen(OUTPUT_FILE,"a+");
double *means = malloc(...);
for(size_t i = 0; ...; ...){
    fscanf(fp,"%*d %lf %*lf %*lf\n", &amp;means[i]);
}
//more stuff
fprintf(fp,...);
fclose(fp);
</code></pre>

<p>And gcc complains about that:</p>

<blockquote>
  <p>warning: use of assignment suppression and length modifier together in gnu_scanf format [-Wformat=]</p>
  
  <p>fscanf(fp,"%*d %lf %*lf %*lf\n", &amp;means[i]);</p>

<pre><code>         ^
</code></pre>
</blockquote>

<p>And I'm not sure what it's trying to tell me, here.</p>