C语言入门课程学习笔记10
- 第48课 - 自定义数据类型（上）
- 实验-typedef
- 实验
- 小结
- 第49课 - 自定义数据类型（中）
- 实验
- 实验
- 小结
- 第50课 - 自定义数据类型（下）
- 实验
- 实验
- 小结
- 第51课 - 多文件程序设计
- 实验
- 实验
- 实验
- 小结
- 第52课 - 课程总结和展望
第48课 - 自定义数据类型（上）
实验-typedef
#include <stdio.h>
#include <string.h>
typedef unsigned char byte;//
void func()
{
typedef byte uint8;
uint8 var = 200;
byte b = var; // 本质为相同类型变量之间的初始化
printf("sizeof(uint8) = %d\n", sizeof(uint8));
printf("var = %d\n", var);
printf("b = %d\n", b);
}
int main()
{
//uint8 var = 1; // ERROR
byte 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]; // 定义数组类型名
typedef int(IFuncII)(int, int); // 定义函数类型名
typedef FArr5* PFArr5;//新定义的类型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;//指针
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));//5
printf("%d\n", npf(2, 3));//5
return 0;
}
实验
#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
*/
小结
第49课 - 自定义数据类型（中）
实验
#include <stdio.h>
#include <string.h>
typedef struct Student Stu;//定义新名称Stu
struct 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 = 910
printf("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; // 只要有了类型声明就可以创建对应的指针变量
// 必须先给出类型的完整定义才能创建相应类型的变量
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);//1
printf("g_pt->b = %d\n", g_pt->b);//2
return 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>'看上去一样，其实是不同的类型
pv = &v2;//warning: assignment to 'struct <anonymous> *' from incompatible pointer type 'struct <anonymous> *' 不可以
return 0;
}
实验
#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};//每个比特位都初始化为0
bw.a = 10;
bw.b = 4; // 4 大于 b 能表示的最大值，因此赋值后 b 回转到 0
bw.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; ==> 浮点型成员不能指点位宽度
};
struct Bits2
{
unsigned char a : 6;
unsigned char b : 6;
unsigned char c : 6;
// unsigned char d : 9; ==> 指定的位宽度不能大于声明类型的位宽度
};
struct Bits3
{
unsigned char a : 4;
unsigned char : 0; // 重启一个存储单元表示新的成员
unsigned char b : 4;
};
int main()
{
printf("sizeof(Bits1) = %d\n", sizeof(struct Bits1));//2+1+1+4=8不对 ？？？？ 4+2+1每4个字节对齐
printf("sizeof(Bits2) = %d\n", sizeof(struct Bits2));//3
printf("sizeof(Bits3) = %d\n", sizeof(struct Bits3));//2
printf("sizeof(float) = %d\n", sizeof(float));
return 0;
}
/*
sizeof(Bits1) = 12
sizeof(Bits2) = 3
sizeof(Bits3) = 2*/
小结
第50课 - 自定义数据类型（下）
实验
#include <stdio.h>
#include <string.h>
union UTest//联合体
{
int a;
float f;
};
struct STest
{
int a;
float f;
};
int isLittleEndian()//低地址存在低字节数据
{
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);//地址一样
printf("struct STest size = %d\n", sizeof(struct STest));
printf("&st.a = %p\n", &st.a);
printf("&st.f = %p\n", &st.f);//地址不一样
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
*/
实验
#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); // 2
printf("s = %d\n", s); // -1
printf("i = %d\n", i); // 7
printf("j = %d\n", j); // 4
d = 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
*/
小结
第51课 - 多文件程序设计
实验
在这里插入代码片
实验
在这里插入代码片
实验
//opm.h
struct Test
{
int a;
int b;
};
extern int g_var; // 声明全局变量时，不需要给出初始值
extern int f_var;
int add(int a, int b);
int mul(int, int); // 进行函数声明的时候，可以省略参数名
extern void test();
//opm.c
#include <stdio.h>
int g_var = 1;
static int f_var = 2; // 只能在当前文件中使用 ==> 静态全局变量
static void func() // 静态函数只能在当前文件中被调用
{
printf("void func() : f_var = %d\n", f_var);
}
void test() // 当前文件中定义的所有函数都可以调用 func() 函数
{
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); // 无法直接使用其他文件中定义的静态全局变量
test();
return 0;
}
小结
第52课 - 课程总结和展望
