This is a simple example sketch to test a 7-Segment display driven by a MAX7219 chip.

MAX7219SegmentId.ino

#include "LedControl.h"

// modified LCDemo7Segment example from the LedControl library

/*
 pin 2 = DataIn 
 pin 3 = CLK 
 pin 4 = LOAD 
 1 = Anzahl hintereinandergeschalteter MAX7219-Chips
 */
LedControl lc=LedControl(2,3,4,1);

void setup() {
  /*
   The MAX72XX is in power-saving mode on startup,
   we have to do a wakeup call
   */
  lc.shutdown(0,false);
  /* Set the brightness to a medium values */
  lc.setIntensity(0,8);
  /* and clear the display */
  lc.clearDisplay(0);

  // set all digits to '8' to make sure all LEDs work
  for (unsigned char i=0; i<8; i++) {
    lc.setDigit(0, i, 8, false);
  }

  delay(1000);

  // print '0' to '7' to digits 0 through 7 to idenfify which is which
  for (unsigned char i=0; i<8; i++) {
    lc.setDigit(0, i, i, false);
  }
}

void loop() { 

}