title: Validating string in c
body: <p>i have a string array  </p>
  
  <p>what i want to do is that check if string only contains numbers if not giving that error: You entered string</p>
  
  <pre><code>void checkTriangle(char *side1[],char *side2[],char *side3[])
  {
      int i;
  
      for(i=0;i&lt;20;i++)
          if(isdigit(side1[i]) == 0)
          {
              printf("You entered string");
              break;
          }
  
  }
  </code></pre>
  
  <p>prints nothing why?</p>