title: Compare two string and remove common letters
body: <p>I am having problem with an exercise, so here is the exercise:</p>
  
  <blockquote>
    <p>Write a program that aids with appropriate messages on the screen to read two character strings <code>str1</code> and <code>str2</code> even which will be given from the keyboard, and then delete all the letters in the variable <code>str1</code>, which also appear in the variable <code>str2</code>. The display shows the final result for checking the correct operation of the program.</p>
  </blockquote>
  
  <p>And here is what I have done so far (I can use only these libraries):</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  #include &lt;stdlib.h&gt;
  #include &lt;string.h&gt;
  
  int main()
  {
      char str1[80], str2[80];
      int megethos1, megethos2,max,i,j;
      printf ("Give the first string: ");
      scanf ("%s", &amp;str1);
      printf ("Give the second string: ");
      scanf ("%s", &amp;str2);
  
      size1= strlen(str1);
      size2= strlen(str2);
  
      for (j=0; j&lt;=megethos2; j++){
          for (i=0; i&lt;=megethos1; i++){
               if (str2[(strlen(str2)-j)]=str1[(strlen(str1)-i)])
                   str1[(strlen(str1)-i)]=' ';
          }
      }
  
      printf (str1);
  
      system("pause");
  
  }
  </code></pre>
  
  <p>So anyone can help me?</p>