Union in c language

  • It is a collection of data of different data type.
  • It is a user defined data type.
  • Data can of int,char,float,double etc. data type.
  • We can access the member of union by making the variable of structure.
  • union keyword is used to create a union.

Note :- Union does not support multiple value simultaneously and it can store only one value at a time.

syntax:

union union_name
{
data_type variable 1;
data_type variable 2;
};
p>Example:

union student
{
char name[100];
int rollno;
float marks;
};
ul class="list">
  • Here student is the name of union.
  • union is a keyword

    • Declaration of union variable method 1

    union student
    {
    char name[100];
    int rollno;
    float marks;
    };
    void main( )
    {
    union student student1;
    };

    Here student1 is the variable of union.

    Declaration of union variable method 2

    union student
    {
    char name[100];
    int rollno;
    float marks;
    }student1;
    int main( )
    {
    return 0;
    }

    Accessing the data members of union :

    The data member of union can be accessed as union_variable.data member for example if we want to access the rollno of student then we can write as student1.rollno

    example – write a program to store and display the student name,rollno and marks.

    Note :- But Union will show only last value correct because it can store only single value at a time.

    I am writing this program here so that you can understand diffrence between structer and union better.

    #include< stdio.h >
    >#include< string. h >
    union student
    {
    char name[100];
    int rollno;
    float marks;
    };
    void main( )
    {
    unionstudent student1;
    (strcpy(student1.name,"Aditya");
    student1.rollno = 07;
    student1.marks = 80.5;
    printf("Student name = %s \n",student1.name);
    printf("Student rollno = %d \n",student1.rollno);
    printf("Student marks = %f \n",student1.marks);
    }

    Output:

    Student name = Aditya
    Student rollno = 07
    Student marks = 85.5