Introduction:
- typedef is a user-defined data type specifier.
- Using typedef we can define identifiers (synonyms) for data types.
- We can use synonyms instead of original data types.
Advantage: Synonyms to data types become more readable than complex identities
Giving the name Integer to int type:
| #include<stdio.h> int main() { typedef int Integer ; Integer a=10,b=20,c; c = a+b; printf(“res : %d\n”,c); return 0; } |
Creating Synonym to Array:
| #include<stdio.h> int main() { typedef int Arry[5]; int i; Array arr = {10,20,30,40,50}; printf(“Array elements are\n”); for(i=0 ; i<5 ; i++) { printf(“%d\n”, arr[i]); } return 0; } |
The main advantage of typedef declaration is giving simple identity for complex types.
For example, char* can simply represent with name String.
| #include<stdio.h> typedef char* String; String read(void); int main() { String name; name = read(); printf(“welcome %s\n”,name); } String read() { String name; printf(“Enter one name : “); gets(name); return name; } |
Typedef declaration to Structures:
- Generally, identity of Structure is a combination of two words.
- For example, struct Emp
- We can give one word to structure type then representation become easy.
| #include<stdio.h> typedef struct Emp { int eno; char* ename; float esal; } Employee; int main() { Employee e; } | #include<stdio.h> struct Emp { int eno; char* ename; float esal; }; int main() { typedef struct Emp Employee; Employee e; } |
By using typedef declarations, we can shorten the size of instructions:
| #include<stdio.h> struct Emp { int eno; char* ename; float esal; }; int main() { typedef struct Emp Employee; typedef struct Emp* Ptr; Ptr e; e = (Ptr)malloc(sizeof(Employee)); } |