title: Toupper not working with char array
body: <p>Thanks for your attention... I am really confused.. Why I cannot convert char type to uppercase with toupper when I gave the char an array... like this "char drh[1]"?</p>
  
  <p>Here is my code.. This code is not finished yet.. I'm stuck in the midway.</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  #include &lt;conio.h&gt;
  #include &lt;stdlib.h&gt;
  #include &lt;ctype.h&gt;
  
  using namespace std;
  int main()
  {
      char nama[50], gender[6], drh[1];
      int tahun_l, usia;
      float berat, tinggi, berat_i;
  
      printf("Masukkan Data Anda\n\n");
      // INPUT ZONE
  
      //First
      printf("Nama\t\t\t\t: ");
      scanf("%[^\n]", &amp;nama);
  
      printf("Tahun Lahir (yyyy)\t\t: ");
      scanf("%d", &amp;tahun_l);
  
      printf("Gol Darah (A/B/C)\t\t: ");
      scanf("%s", &amp;drh);
  
      system("cls");
  
      //Second
      printf("Masukkan Data Anda\n\n");
  
      printf("Nama\t\t\t\t: %s\n", nama);
      fflush(stdin);
  
      printf("Tahun Lahir (yyyy)\t\t: %d\n", tahun_l);
      fflush(stdin);
  
      printf("Gol Darah (A/B/O)\t\t: %s\n", drh);
      drh = toupper(drh); //not working
      fflush(stdin);
  
      printf("Jenis Kelamin (Pria/Wanita)\t: ");
      scanf("%s", &amp;gender);
  
      printf("Berat Badan (kg)\t\t: ");
      scanf("%f", &amp;berat);
  
      printf("Tinggi Badan (cm)\t\t: ");
      scanf("%f", &amp;tinggi);
  
      //FORMULA ZONE
      usia    = 2008 - tahun_l;
      berat_i = tinggi - 100 - (0.1 * (tinggi - 100));
      //OUTPUT ZONE
      printf("\n%s, berdasarkan data yang Anda masukkan,\n", nama);
      printf("Anda berjenis kelamin %s, saat ini Anda berusia %d tahun,\n", gender, usia);
      printf("Berat badan = %.2f kg, tinggi badan = %.2f cm, golongan darah = %s \n", berat, tinggi, drh);
      printf("\nBerat badan ideal adalah %.2f", berat_i);
  
      getche();
      return 0; 
  }
  </code></pre>