Difference Between Type Casting and Type Conversion

The basic difference between type conversion and type casting, i.e. type conversion is made “automatically” by compiler whereas, type casting is to be “explicitly done” by the programmer.

The two terms “type casting” and “type conversion” occur when there is a need to convert one data type to another. When the two types are compatible with each other, then the conversion of one type to other is done automatically by the compiler. Let’s discuss the difference both type casting and conversion with the help of comparison chart.

Content: Type Casting Vs Type Conversion

1. Comparison Chart
2. Definition
3. Key Differences
4. Conclusion

Comparison Chart

Basis for Comparison	Type Casting	Type Conversion
Meaning	One data type is assigned to another by the user, using a cast operator then it is called "Type Casting".	Conversion of one data type to another automatically by the compiler is called "Type Conversion".
Applied	Type casting can also be applied to two 'incompatible' data types.	Type conversion can only be implemented when two data types are 'compatible'.
Operator	For casting a data type to another, a casting operator '()' is required.	No operator required.
Size of Data Types	Destination type can be smaller than source type.	Here the destination type must be larger than source type.
Implemented	It is done during program designing.	It is done explicitly while compiling.
Conversion type	Narrowing conversion.	Widening conversion.
Example	int a; byte b; ... ... b= (byte) a;	int a=3; float b; b=a; // value in b=3.000.

Definition of Type Casting

Type casting can be defined as, casting of one data type to another data type, by the programmer, at the time of program design. Automatic conversion of one data type to another is not possible all the time. It may be the condition that the ‘destination type’ is smaller than the ‘source type’. Therefore, the programmer has to cast the larger data type explicitly to smaller data type using the casting operator ‘( )’. As the larger data type is modulated to the smaller data type, it is also called ‘narrowing conversion’.Declaration

destination_type = (target_type) variable/value

//target type is a type in which you want to convert the source type, it is always the destination type.

Example

Let’s understand it with an example. You want to convert the data type ‘int’ to ‘byte’. Now, as ‘byte’ is smaller than ‘int’, type conversion is not allowed. Here, we had to implicitly convert ‘int’ into ‘byte’ by using casting operator ‘()’. As ‘int’ is larger than ‘byte’, the size of ‘int’ will be reduced to “int mod byte” range.

int a;
byte b;
...
...
b=(byte)a;

When the ‘float’ is converted to ‘int’, the size of float gets truncated, as ‘int’ does not store the fractional value. If the size of the destination type is too small for the source type to fit into, then source type is modulo destination type ‘range’. Casting can also be applied when data types are compatible. It is good practice to use type casting wherever type conversion is needed.

Definition of Type Conversion

Type conversion is the automatic conversion of one data type to another whenever required, done explicitly by the compiler. But there are two conditions to be satisfied before type conversion.

• Source and destination type must be compatible.
• Destination type must be larger than source type.

These two conditions should satisfy to achieve type conversion, and this kind of conversion is called ‘widening conversion’, as a smaller type is converted to larger type, widening of type occurs. For this widening conversion, numeric types as ‘int’, ‘float’ are compatible with each other while numeric to char and boolean or char to boolean is also not compatible.

Example

This example will provide a better view of this

int a=3;
float b;
b=a;  // value in b=3.000.

Here, ‘int’ is converted to ‘float’ which is larger than ‘int’, so widening of source type occurs. Here, no casting operator is required as the compiler will do it explicitly.

Conclusion

It can be concluded that type conversion and type casting, both perform the task of converting one data type to another but differ in a sense that type casting is done by the programmer, using cast operator'()’ and type conversion is done by the compiler, and it doesn’t use any operator.