Arduino Timer/Clock

I Tried The code on arduino uno with keypad lcd but it stops compiling:
Any guess to get it running?

It says:
time_t does not name a type

Button:57: error: 'time_t' does not name a type
Button.ino: In function 'void setup()':
Button:79: error: 'requestSync' was not declared in this scope
Button:79: error: 'setSyncProvider' was not declared in this scope
Button.ino: In function 'void loop()':
Button:88: error: 'timeStatus' was not declared in this scope
Button:88: error: 'timeNotSet' was not declared in this scope
Button:91: error: 'setTime' was not declared in this scope
Button:95: error: 'timeStatus' was not declared in this scope
Button:95: error: 'timeNotSet' was not declared in this scope
Button:97: error: 'timeSet' was not declared in this scope
Button.ino: In function 'void digitalClockDisplay()':
Button:124: error: 'day' was not declared in this scope
Button:126: error: 'day' was not declared in this scope
Button:129: error: 'month' was not declared in this scope
Button:131: error: 'month' was not declared in this scope
Button:133: error: 'year' was not declared in this scope
Button:136: error: 'hour' was not declared in this scope
Button:141: error: 'hour' was not declared in this scope
Button:142: error: 'minute' was not declared in this scope
Button:143: error: 'second' was not declared in this scope
Button.ino: In function 'void processSyncMessage()':
Button:169: error: 'time_t' was not declared in this scope
Button:169: error: expected `;' before 'pctime'
Button:173: error: 'pctime' was not declared in this scope
Button:176: error: 'pctime' was not declared in this scope
Button:176: error: 'setTime' was not declared in this scope
Button.ino: At global scope:
Button:181: error: 'time_t' does not name a type
Button.ino: In function 'void setDateTime()':
Button:515: error: 'setTime' was not declared in this scope