int isgraph(int chr);

checks for any printing character except space (' ')

#include <stdio.h> /* including standard library */
//#include <windows.h> /* uncomment this for Windows */
 
#include <ctype.h>
 
int main ( void )
{
  int i;
  char string[11]="Test\n-!&%1";
  for (i=0; i <= 11;i++)
    {
     if ( isgraph(string[i]) != 0 )
      {
       printf("Character %i is a graph\n",i);
      }
    }
  return 0;
}

  output:
  user@host:~$ ./isgraph 
  Character 0 is a graph
  Character 1 is a graph
  Character 2 is a graph
  Character 3 is a graph
  Character 5 is a graph
  Character 6 is a graph
  Character 7 is a graph
  Character 8 is a graph
  Character 9 is a graph