data type conversion

Type Conversion in C

• Type conversion occurs when the expression has data of mixed data types. 
• example of such expression include converting an integer value in to a float value, or assigning the value of the expression to a variable with different data type.
• In type conversion, the data type is promoted from lower to higher because converting higher to lower involves loss of precision and value.
• For type conversion, C following some General rules explained below 
  • Integer types are lower than floating point types
  • Signed types are lower than unsigned types
  • Short whole number types are lower than longer types
  • double>float>long>int>short>char

In other word :

Type Conversion refers to translating of values (roughly speaking, contents of the object), so that they may be interpreted as belonging to a new type.

A type cast is basically a conversion from one type to another. There are two types of type conversion:

1. Implicit Type Conversion Also known as ‘automatic type conversion’.
   • Done by the compiler on its own, without any external trigger from the user.
   • Generally takes place when in an expression more than one data type is present. In such condition type conversion (type promotion) takes place to avoid lose of data.
   • All the data types of the variables are upgraded to the data type of the variable with largest data type.

         
            bool -> char -> short int -> int -> 
            unsigned int -> long -> unsigned -> 
            long long -> float -> double -> long double
     

   • It is possible for implicit conversions to lose information, signs can be lost (when signed is implicitly converted to unsigned), and overflow can occur (when long long is implicitly converted to float).
   Example of Type Implicit Conversion:

   // An example of implicit conversion #include<stdio.h> int main() {     int x = 10;    // integer x     char y = 'a';  // character c       // y implicitly converted to int. ASCII     // value of 'a' is 97     x = x + y;          // x is implicitly converted to float     float z = x + 1.0;       printf("x = %d, z = %f", x, z);     return 0; }

   Output:

   x = 107, z = 108.000000

2. Explicit Type Conversion– This process is also called type casting and it is user defined. Here the user can type cast the result to make it of a particular data type.
   The syntax in C:

   (type) expression

   Type indicated the data type to which the final result is converted.

   // C program to demonstrate explicit type casting #include<stdio.h>   int main() {     double x = 1.2;       // Explicit conversion from double to int     int sum = (int)x + 1;       printf("sum = %d", sum);       return 0; }

   Output:

   sum = 2

   Advantages of Type Conversion
   • This is done to take advantage of certain features of type hierarchies or type representations.
   • It helps us to compute expressions containing variables of different data types.