C語言入門課程學習筆記10
- 第48課 - 自定義數據類型（上）
- 實驗-typedef
- 實驗
- 小結
- 第49課 - 自定義數據類型（中）
- 實驗
- 實驗
- 小結
- 第50課 - 自定義數據類型（下）
- 實驗
- 實驗
- 小結
- 第51課 - 多文件程序設計
- 實驗
- 實驗
- 實驗
- 小結
- 第52課 - 課程總結和展望
第48課 - 自定義數據類型（上）
實驗-typedef
#include <stdio.h>
#include <string.h>typedef unsigned char byte;//void func()
{typedef byte uint8;uint8 var = 200;byte b = var; // 本質為相同類型變量之間的初始化printf("sizeof(uint8) = %d\n", sizeof(uint8));printf("var = %d\n", var);printf("b = %d\n", b);
}int main()
{//uint8 var = 1; // ERRORbyte b = 128;func();printf("sizeof(byte) = %d\n", sizeof(byte));printf("b = %d\n", b);return 0;
}
/*
sizeof(uint8) = 1
var = 200
b = 200
sizeof(byte) = 1
b = 128
*/
#include <stdio.h>
#include <string.h>typedef float(FArr5)[5]; // 定義數組類型名
typedef int(IFuncII)(int, int); // 定義函數類型名typedef FArr5* PFArr5;//新定義的類型PFArr5
typedef IFuncII* PIFuncII;float g_arr[5] = {0.1, 0.2, 0.3};int add(int a, int b)
{return a + b;
}int main()
{FArr5* pa = &g_arr; // float(*)[5]IFuncII* pf = add; // int(*)(int,int)PFArr5 npa = pa;//指針PIFuncII npf = pf;int i = 0;for(i=0; i<5; i++){printf("%f\n", (*pa)[i]);//元素值printf("%f\n", (*npa)[i]);}printf("%d\n", pf(2, 3));//5printf("%d\n", npf(2, 3));//5return 0;
}
實驗
#include <stdio.h>
#include <string.h>struct Student
{char name[20];int id;short major;
};int main()
{struct Student s1 = {"Delphi", 908, 1};struct Student s2 = s1;printf("s1.name = %s\n", s1.name);printf("s1.id = %d\n", s1.id);printf("s1.major = %d\n", s1.major);strcpy(s2.name, "Tang");s2.id = 909;s2.major = 2;printf("s2.name = %s\n", s2.name);printf("s2.id = %d\n", s2.id);printf("s2.major = %d\n", s2.major);return 0;
}
/*
s1.name = Delphi
s1.id = 908
s1.major = 1
s2.name = Tang
s2.id = 909
s2.major = 2
*/小結
第49課 - 自定義數據類型（中）
實驗
#include <stdio.h>
#include <string.h>typedef struct Student Stu;//定義新名稱Stustruct Student
{char name[20];int id;short major;
};int main()
{Stu s;//Stu* ps = &s;strcpy(ps->name, "Delphi");ps->id = 1;ps->major = 908;(*ps).major = 910; // ==> s.major = 910printf("s.name = %s\n", s.name);printf("s.id = %d\n", s.id);printf("s.major = %d\n", s.major);return 0;
}
/*
s.name = Delphi
s.id = 1
s.major = 910*/
#include <stdio.h>
#include <string.h>struct Test;
struct Test* g_pt; // 只要有了類型聲明就可以創建對應的指針變量// 必須先給出類型的完整定義才能創建相應類型的變量
struct Test
{int a;int b;
};int main()
{struct Test t;t.a = 1;t.b = 2;g_pt = &t;printf("g_pt = %p\n", g_pt);printf("g_pt->a = %d\n", g_pt->a);//1printf("g_pt->b = %d\n", g_pt->b);//2return 0;
}
/*
g_pt = 000000000061FE18
g_pt->a = 1
g_pt->b = 2
*/#include <stdio.h>
#include <string.h>int main()
{struct { int a, b; } v1;struct { int a, b; } v2;struct { int a, b; }*pv;v1.a = 1;v1.b = 2;// v2 = v1;//？？error: incompatible types when assigning to type 'struct <anonymous>' from type 'struct <anonymous>'看上去一樣，其實是不同的類型pv = &v2;//warning: assignment to 'struct <anonymous> *' from incompatible pointer type 'struct <anonymous> *' 不可以return 0;
}
實驗
#include <stdio.h>
#include <string.h>struct BW
{unsigned char a : 4;unsigned char b : 2;unsigned char c : 2;
};int main()
{struct BW bw = {0};//每個比特位都初始化為0bw.a = 10;bw.b = 4; // 4 大于 b 能表示的最大值，因此賦值后 b 回轉到 0bw.c = 3;printf("sizeof(struct BW) = %d\n", sizeof(struct BW));printf("bw.a = %d\n", bw.a);printf("bw.b = %d\n", bw.b);printf("bw.c = %d\n", bw.c);return 0;
}
/*
sizeof(struct BW) = 1
bw.a = 10
bw.b = 0
bw.c = 3
*/#include <stdio.h>
#include <string.h>struct Bits1
{int a : 16;short b : 8;char c : 8;float f; // float f : 32; ==> 浮點型成員不能指點位寬度
};struct Bits2
{unsigned char a : 6;unsigned char b : 6;unsigned char c : 6;// unsigned char d : 9; ==> 指定的位寬度不能大于聲明類型的位寬度
};struct Bits3
{unsigned char a : 4;unsigned char : 0; // 重啟一個存儲單元表示新的成員unsigned char b : 4;
};int main()
{printf("sizeof(Bits1) = %d\n", sizeof(struct Bits1));//2+1+1+4=8不對 ？？？？ 4+2+1每4個字節對齊printf("sizeof(Bits2) = %d\n", sizeof(struct Bits2));//3printf("sizeof(Bits3) = %d\n", sizeof(struct Bits3));//2printf("sizeof(float) = %d\n", sizeof(float));return 0;
}
/*
sizeof(Bits1) = 12
sizeof(Bits2) = 3
sizeof(Bits3) = 2*/小結
第50課 - 自定義數據類型（下）
實驗
#include <stdio.h>
#include <string.h>union UTest//聯合體
{int a;float f;
};struct STest
{int a;float f;
};int isLittleEndian()//低地址存在低字節數據
{union{int i;char a[4];} test = {0};test.i = 1;return (test.a[0] == 1);
}int main()
{union UTest ut = {987654321};struct STest st = {987654321, 0.1f};printf("union UTest size = %d\n", sizeof(union UTest));printf("&ut.a = %p\n", &ut.a);printf("&ut.f = %p\n", &ut.f);//地址一樣printf("struct STest size = %d\n", sizeof(struct STest));printf("&st.a = %p\n", &st.a);printf("&st.f = %p\n", &st.f);//地址不一樣printf("ut.a = %d\n", ut.a);//printf("ut.f = %f\n", ut.f);//ut.f = 987654321.0f;printf("ut.a = %d\n", ut.a);printf("ut.f = %f\n", ut.f);printf("System Endian: %d\n", isLittleEndian());return 0;
}
/*
union UTest size = 4
&ut.a = 000000000061FE1C
&ut.f = 000000000061FE1C
struct STest size = 8
&st.a = 000000000061FE14
&st.f = 000000000061FE18
ut.a = 987654321
ut.f = 0.001697
ut.a = 1315666339
ut.f = 987654336.000000
System Endian: 1
*/
實驗
#include <stdio.h>
#include <string.h>enum Day { MON = 1, TUE, WED, THU, FRI, SAT, SUN };
enum Season { Spring, Summer = 3, Autumn, Winter = -1 };enum { CONSTANT = 12345 };int main()
{enum Day d = TUE;enum Season s = Winter;int i = SUN;int j = Autumn;printf("d = %d\n", d); // 2printf("s = %d\n", s); // -1printf("i = %d\n", i); // 7printf("j = %d\n", j); // 4d = 0;s = -2;printf("d = %d\n", d);printf("s = %d\n", s);printf("sizeof(enum Day) = %d\n", sizeof(enum Day));printf("sizeof(enum Season) = %d\n", sizeof(enum Season));printf("CONSTANT = %d\n", CONSTANT);// CONSTANT = 54321;return 0;
}
/*
d = 2
s = -1
i = 7
j = 4
d = 0
s = -2
sizeof(enum Day) = 4
sizeof(enum Season) = 4
CONSTANT = 12345*/小結
第51課 - 多文件程序設計
實驗
在這里插入代碼片
實驗
在這里插入代碼片
實驗
//opm.h
struct Test
{int a;int b;
};extern int g_var; // 聲明全局變量時，不需要給出初始值
extern int f_var;int add(int a, int b);
int mul(int, int); // 進行函數聲明的時候，可以省略參數名extern void test();//opm.c
#include <stdio.h>int g_var = 1;
static int f_var = 2; // 只能在當前文件中使用 ==> 靜態全局變量static void func() // 靜態函數只能在當前文件中被調用
{printf("void func() : f_var = %d\n", f_var);
}void test() // 當前文件中定義的所有函數都可以調用 func() 函數
{func();
}int add(int a, int b)
{return a + b;
}int mul(int a, int b)
{return a * b;
}
//main.c
#include <stdio.h>
#include <string.h>
#include "opm.h"int main()
{struct Test t = {1, 2};printf("a + b = %d\n", add(t.a, t.b));printf("a * b = %d\n", mul(t.a, t.b));printf("g_var = %d\n", g_var);// printf("f_var = %d\n", f_var); // 無法直接使用其他文件中定義的靜態全局變量test();return 0;
}
小結
第52課 - 課程總結和展望
)
