title: Problems using main(int argc,char *argv[])
body: <pre><code>#include&lt;stdio.h&gt;
  #include&lt;string.h&gt;
  int main(int argc,char *argv[])
  {
      char string[]="#";
      printf("%s\n",argv[1]);
      printf("%s\n",argv[2]);
      printf("%s\n",argv[3]);
      strcat(argv[1],string);
      printf("argv[1] is %s\n",argv[1]);
      printf("argv[2] is %s\n",argv[2]);
      printf("argv[3] is %s\n",argv[3]);
      return 0;
  }
  </code></pre>
  
  <p>when I use strcat() to add something to the end of the argv[1],argv[2] will be lost( strlen(argv[2]) changes to 0 after use strcat ).But argv[3] has no change .Why???</p>