C Type Conversion
Type Conversion
In some cases, you will need to convert the value of one data type to another type. This is known as type conversion.
For example, if you try to divide two integers, 5 by 2, you
would
expect the result to be 2.5. But since we are working with integers (and not
floating-point values), the result is actually just 2:
To get the right result, you need to know how type conversion works.
There are two types of conversion in C:
- Implicit Conversion (automatically)
- Explicit Conversion (manually)
Implicit Conversion
Implicit conversion is done automatically by the compiler when you assign a value of one type to another.
For example, if you assign an int value to a
float type:
Example
// Automatic conversion: int to float
float myFloat = 9;
printf("%f",
myFloat); // 9.000000
Try it Yourself »
As you can see, the compiler automatically converts the int value 9 to a
float value of 9.000000.
This can be risky, as you might lose control over specific values in certain situations.
Especially if it was the other way around - the following example
automatically converts the float value 9.99 to an int value of 9:
Example
// Automatic conversion: float to int
int myInt = 9.99;
printf("%d",
myInt); // 9
Try it Yourself »
What happened to .99? We might want that
value in our program!
So be careful. It is important that you know how the compiler work in these situations, to
avoid unexpected results.
As another example, if you divide two integers: 5 by 2,
you know that the sum is 2.5. And as you know from the beginning
of this page, if you store the sum as an integer, the result will
only display the number
2. Therefore, it would be better to store the sum
as a
float or a double, right?
Why is the result 2.00000 and not 2.5? Well, it is because
5 and 2 are still integers in the division.
In this case, you need to manually convert the integer values to
floating-point values, to get the desired output (see below).
Explicit Conversion
Explicit conversion is done manually by placing the type in parentheses ()
in front of the value.
Considering our problem from the example above, we can now get the right result:
Example
// Manual conversion: int to float
float sum = (float) 5 / 2;
printf("%f", result); // 2.500000
Try it Yourself »
You can also place the type in front of a variable:
Example
int num1 = 5;
int num2 = 2;
float result = (float) num1 / num2;
printf("%f", result); // 2.500000
Try it Yourself »
