Use of trailing characters in JAVA/C++ -

I was a little curious why we use characters in Java / C ++ . E.g.,

  float F = 23f;   
 We can also write  
  float f = 23;   
 Both have the effect.   
 
 
 This is important when you have rigorous numbers in mathematical operations.  
 For example:  
  5/2 == 2 5.0f / 2.0f = 2.5f 5.0 / 2.0 = 2.5 / You doubles in the suffix of 'F' Doubles for 5.0d / 2.0d = 2.5d // can also be used as "D"   
 Apart from this, there will be a different result:  
  blah / 3.141592653592 // This gives a precise double blah / 3.141592653592 F / returns it gives a less precise float