title: How to toupper char array in c?
body: <p>whats wrong here?</p>
  
  <p>I want to check if the char in char array islower, so if it is it should be changed in uppercase. </p>
  
  <pre><code>#include &lt;stdio.h&gt;
  
  int main(int argc, char *argv[]) {
      char arr[100];
      scanf("%s",&amp;arr);
      for(int i=0;i&lt;sizeof(arr);i++){
          if(int islower(arr[i])){
              arr[i] = toupper(arr[i]);
          }
      }
      printf("%s",arr);
      return 0;
  }
  </code></pre>