Introduction

The conversion of a variable from one data type to another data type is referred to as typecasting in C.

For example, converting a float value to an int value.

Conversion of 25.5555 to 25 is done by typecasting.

There are two types of type conversions:

1. Implicit conversion
2. Explicit conversion

Implicit Type Conversion in C

Is it possible to add a numeric value and a character value like ‘q+9’?

Yes, ‘q+9’ is a valid expression in C language because we have some numeric value corresponding to every character in C language. And the compiler will automatically convert q to its ASCII value and then add 9 to it. This automatic conversion is known as the implicit conversion of typecasting. The value ‘q’, which is a char type, automatically gets converted into int type by the compiler.

Note: In our programs, if we perform any arithmetic operations consisting of the, character value, their conversion is done automatically from char to int.

Example

#include<stdio.h>
int main()
{
            int x, s;
            char y;
           
            printf("enter a character value: ");
            scanf("%c",&y);
           
            printf("enter an integer value: ");
            scanf("%d",&x);
           
            s=x-y;
            printf("\nDifference: %d",s);
           
            return 0;
}

Output

When the two variables x and y having values ‘25’ and ‘d’ respectively are subtracted, the resultant value is -75 because the ASCII value of ‘d’ is 100 and ‘25-100’ gives -75.

Explicit Type Conversion in C

We, as programmers, have complete control to convert any value from one data type to another.

The type of conversion, when done manually, is called an explicit conversion.

Syntax: (data-type) value;

In the above syntax, ‘value’ will get converted to the data type we want.

Example

Look at the program written below to understand explicit conversion.

#include<stdio.h>
int main()
{
            float a;
            printf("enter a float value:\n");
            scanf("%f",&a);
           
            int b;
            b=(int)a;
            printf("value after type conversion:%d",b);
}

Output

‘a’ is declared as float type, and we converted that into int type.

Alternative Code

The code written below is the same as the code written above, with some changes.

#include<stdio.h>
int main()
{
            float a;
            printf("enter a float value:\n");
            scanf("%f",&a);
            printf("value after type conversion:%d",(int)a);
}