C Language Learning 014: structured data types

Basic use of structs

1#include <stdio.h>2 3 //Defining data Structures4 structfish{5     Const Char*name;6     Const Char*species;7     intteeth;8     intAge ;9 };Ten  One voidCatalogstructFish f) { Aprintf"%s is a%s with%i teeth. He is%i\n", f.name,f.species,f.teeth,f.age);//access the fields of the structure - } -  the intMain () { -     //declaring struct variables -     structFish snappy={"Snappy","Piranha", the,4}; - catalog (snappy); +     return 0; -}

When you assign a struct variable to another structure variable, the computer creates a completely new copy of the structure, and then copies each of the fields, and if there is a pointer in the struct, the value of the pointer is copied only

    struct fish snappy={"snappy","Piranha",69 ,4};     struct fish gnasher=snappy;

Structures can also be nested using

1#include <stdio.h>2 3 structpreferences{4     Const Char*Food ;5     floatexercise_hours;6 };7 8 structfish{9     Const Char*name;Ten     Const Char*species; One     intteeth; A     intAge ; -     structPreferences care;//structure nested in fish preferences - }; the  - voidCatalogstructFish f) { -printf"%s is a%s with%i teeth. He is%i\n", f.name,f.species,f.teeth,f.age);//access the fields of the structure -     //accessing a struct in a struct body +printf"%s like to eat%s\n", F.name,f.care.food); -printf"%s like to exercise%f hours\n", f.name,f.care.exercise_hours); + } A  at intMain () { -     structFish snappy={"Snappy","Piranha", the,4,{"Meat",7.5}}; - catalog (snappy); -     return 0; -}

Simpler to create structure variables

Naming structures by using typedef so that you can omit the struct keyword when you create a struct variable

#include <stdio.h>typedefstructcell_phone{intCell_no; Const Char*Wallpapaer;} Phone;//phone is a type name (alias for Cell_phone)intMain () {phone P={5555,"Sinatra.png"}; printf ("Number %i\n", P.cell_no); return 0;}

We can also omit the structure's name definition structure directly, which is the so-called anonymous structure

1 struct {2     int Cell_no; 3     Const Char *Wallpapaer; 4 } phone;

passing struct pointers

When assigning a struct to another structure, we know that a new copy is created, and if we want to update the original structure with the assigned structure, we need to use the struct pointer

1#include <stdio.h>2 3typedefstruct {4     intCell_no;5     Const Char*Wallpapaer;6 } phone;7 8 intMain () {9Phone p={5555,"Sinatra.png"};TenPhone p2=p; Onep2.cell_no=4444; Aprintf"p.cell_no:%i p2.cell_no:%i\n", p.cell_no,p2.cell_no); -phone* p3=&p;//assign the address of structure p to *p3 -(*P3). cell_no=6666; theprintf"p.cell_no:%i p2.cell_no:%i p3.cell_no:%i\n", P.cell_no,p2.cell_no, (*p3). cell_no); -     return 0; -}

Because we often put (*P2). Wallpapaer errors written *p2.wallpapaer, they are not equivalent, so C language developers have designed a simpler way to represent the structure of pointers

1 int Main () {2      phone p={5555,"sinatra.png"}; 3      phone* p2=&p; 4      printf ("p2->wallpapaer:%s = (*p2). wallpapaer:%s\n", P2->wallpapaer, (*P2). Wallpapaer); // 5     return 0 ; 6 }

C language Learning 014: structured data types