The C programming language has many features which may help programmers in easy coding. Unions are defined as a special data type. It is used to store a collection of different types of data. Unions are like structures. With the help of unions, you can use the same memory location for multiple purposes.<\/p>\n
Unions are like structures. It is used to store different types of data in the same memory location. The only difference between structures and unions is that unions only hold one value at a time whereas structures hold all their members. With the help of unions, you can define many members but only one of them can contain value at one time.<\/p>\n
As we know that unions can contain many members of different data types but it cannot handle all the members at the same time.<\/p>\n
The union<\/strong> keyword is used to define the unions.<\/p>\n Syntax:-<\/strong><\/p>\n Example of Union in C<\/strong><\/p>\n In the above, we have defined an union type named detail<\/strong> which has three members of different data types such as integer, character and float. Data type will occupy 30 bytes of memory space because character data type occupies 30 bytes of space and this is the maximum space which is occupied.<\/p>\n Union is a user defined data type. To use and allocate memory for the union type, we first need to create variables.<\/p>\n Example of Creating union variables inside main() function<\/strong><\/p>\n In the above example, we created three union type variables. You can also create variables like below:-<\/p>\n Creating union variables outside the main() function<\/strong><\/p>\n In both examples, we created union variables such as emp1 and a union pointer to emp2 to union type detail.<\/p>\n Example:- Basic example of union in C<\/strong><\/p>\n Output<\/strong><\/p>\n To access the members of union type, we use the . operator. And -> is used to access pointer variables.<\/p>\n Example:- Accessing members of union in C<\/strong><\/p>\n Output<\/strong><\/p>\n In the above example, we used web.name to access name for variable web and also used web.tutorial to access tutorial for variable web.<\/p>\n The main difference between union and structure is that in structure, each variable has its own storage location but in union, all members use the size of its largest data member.<\/p>\n There are a couple of differences between union and structure. Let\u2019s discuss below:-<\/p>\n Let\u2019s take a look at the below example:-<\/p>\n Output<\/strong><\/p>\n From the above example, we can see that:-<\/p>\n The size of s2[32] is 32 bytes. But in union the size of detail is 32 bytes because the size of a union variable will always be the largest of its members.<\/p>\n We can also use pointers to unions like structures. To access the members of unions, you have to use the arrow operator ->.<\/p>\n Example:- pointer to unions<\/strong><\/p>\n Output<\/strong><\/p>\n Output<\/strong><\/p>\n TechVidvan TUtorial: Use of Unions in C!<\/p>\n Age of the student is: 754 From the above example, it is proved that you can only access one member at one time.<\/p>\n Only big disadvantage is that only last entered data can be stored in union.<\/p>\n Union is like structure. It is a user-defined data type. It is used to store different types of data in the same memory location.<\/p>\n The main difference between union and structure is that in structure, each variable has its own storage location but in union, all members use the size of its largest data member.<\/p>\n","protected":false},"excerpt":{"rendered":" The C programming language has many features which may help programmers in easy coding. Unions are defined as a special data type. It is used to store a collection of different types of data....<\/p>\n","protected":false},"author":1,"featured_media":81693,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3510],"tags":[3735,3736,3737,3738],"class_list":["post-81481","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-c-programming","tag-adavantages-and-disadvantages-of-real-time-processing","tag-advantages-of-union-in-c","tag-disadvantages-of-union-in-c","tag-union-in-c"],"yoast_head":"\nunion UnionName{\n\/\/ member definitions;\n}\n<\/pre>\nunion detail{\nint id;\nchar name[30];\nfloat salary;\n};\n<\/pre>\nCreating union variables in C<\/h3>\n
union detail{\nint id;\nchar name[30];\nfloat salary;\n};\nint main(){\nunion detail emp1,*emp2;\nreturn 0;\n}\n<\/pre>\nunion detail{\nint id;\nchar name[30];\nfloat salary;\n}emp1, *emp2;\n<\/pre>\n#include <stdio.h>\nunion detail{\n int bill;\n char name[50];\n};\nint main( ) {\nunion detail a; \t \nprintf(\"Total Memory size occupied by detail union type is: %d\\n\", sizeof(a));\nreturn 0;\n}\n<\/pre>\nAccessing members of union in C<\/h3>\n
#include<stdio.h>\n#include<string.h>\nunion bestWebsite\n{\n char name[20];\n char tutorial[50];\n};\n \nvoid main( )\n{\nunion bestWebsite web;\nstrcpy( web.name, \"TechVidvan Tutorials!\");\nprintf(\"Best Website to learn C programming is: %s\\n\",web.name);\nstrcpy(web.tutorial, \"union in C!\"); \nprintf(\"Now you are doing: %s\\n\",web.tutorial);\n}\n<\/pre>\n
\nNow you are doing: union in C!<\/div>\nDifference between union and structure in C<\/h3>\n
\n\n
\n Distinctive Feature<\/b><\/td>\n Structure<\/b><\/td>\n Union<\/b><\/td>\n<\/tr>\n \n Keyword<\/b><\/td>\n It begins with the struct keyword.<\/span><\/td>\n It begins with the union keyword.<\/span><\/td>\n<\/tr>\n \n Memory location<\/b><\/td>\n In structure, all members of a structure have their own individual memory location for their storage.<\/span><\/td>\n In union, all members of a union share the same memory location for their storage.<\/span><\/td>\n<\/tr>\n \n Initialization<\/b><\/td>\n You can initialize many data members of a structure at one time.<\/span><\/td>\n But union forbids the initialization of all its members.<\/span><\/td>\n<\/tr>\n \n Size<\/b><\/td>\n Structure size depends on the sum of the individual sizes of its members.<\/span><\/td>\n In union, total size is the largest size among its data members.<\/span><\/td>\n<\/tr>\n \n Access<\/b><\/td>\n All data members of the structure can be accessed at one time.\u00a0<\/span><\/td>\n In union, you can access one data member at one time.<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n #include <stdio.h>\nunion detail\n{\n char s1[32];\n int id;\n}employee;\n\nstruct custom\n{\n char s2[32];\n int id_branch;\n}worker;\n\nint main()\n{\nprintf(\"TechVidvan Tutorials: Difference between union and structure!\\n\");\nprintf(\"Union size is: %d bytes\\n\", sizeof(employee));\nprintf(\"Structure size is: %d bytes\", sizeof(worker));\nreturn 0;\n}\n<\/pre>\n
\nUnion size is: 32 bytes
\nStructure size is: 36 bytes<\/div>\n\n
\nSize of id_branch is 4 bytes.<\/p>\n\n
Pointer to union in C<\/h3>\n
#include <stdio.h>\nunion point {\n int a;\n double c;\n};\nint main()\n{\n union point point1;\n point1.a = 10;\n union point* point2 = &point1;\n printf(\"TechVidvan Tutorials: pointers to union!\\n\");\n printf(\"%d\", point2->a);\n return 0;\n}\n<\/pre>\n
\n10<\/div>\nUse of Union in C<\/h3>\n
#include <stdio.h>\nunion student\n{\nint age;\nint total_marks;\n};\nint main()\n{\nprintf(\"TechVidvan TUtorial: Use of Unions in C!\\n\\n\");\nunion student s1;\ns1.age = 20;\ns1.total_marks = 754;\nprintf(\"Age of the student is: %d\\n\",s1.age);\nprintf(\"Total marks of the student is: %d\\n\",s1.total_marks);\nreturn 0;\n}\n<\/pre>\n
\nTotal marks of the student is: 754<\/p>\n<\/div>\nAdvantages of Union in C<\/h3>\n
\n
\nunion.<\/li>\nDisadvantages of Union in C<\/h3>\n
Applications of C Union<\/h3>\n
\n
Summary<\/h3>\n