C语言基础知识学习经典入门
目录
1 本课概要... 1
2 C语言入口方法... 1
3 C语言标准输入与输出... 1
4 C语言方法调用... 2
5 C语言宏定义 – 在编译阶段... 2
6 C语言宏方法定义 – 在编译阶段，无类型... 3
7 C语言条件判断... 3
8 C语言循环... 4
9 C语言结构体 – 存储数据的集合 – 结构体的赋值，直接是内存的拷贝... 5
10 C语言结构体指针 - 同一块内存... 5
11 C语言函数指针... 6
12 C语言typedef关键字... 6
13 C语言面向对象 – 思维方式... 7
14 C语言引入自定义头文件... 9
15 C语言字符串操作 - sprintf 10
16 C语言文件操作 – fprintf、 fread. 10
17 C语言实现猜数字小游戏... 11
1 本课概要
2 C语言入口方法
#include
int main(int argc, const char * argv[]) { //argc从控制台传进来参数的数量，argv[]从控制台传入参数的值
int i;
for (i = 0; i < argc; i++){
printf("%s\n",argv[i]);
}
return 0; //C语言程序异常退出的代码，是返回给操作系统的，0表示正常退出
}
C:\Users\Administrator\.CLion12\system\cmake\generated\45b5718a\45b5718a\Debug>C01HelloC.exe //当前应用程序的文件名
C01HelloC.exe //当前控制台所传入的第一个参数
C:\Users\Administrator\.CLion12\system\cmake\generated\45b5718a\45b5718a\Debug>C01HelloC.exe Hello C "Hello World"
C01HelloC.exe
Hello
C
Hello World
3 C语言标准输入与输出
#includeint main() { printf("Hello %d",100); printf("Hello %d\n",50); puts("Hello C"); puts("Hello world"); char buf[100]; gets(buf); puts(buf); int a; scanf("%d",&a); printf("%d\n",a); return 0; }
4 C语言方法调用
#includeint max(int a, int b){ if (a>b){ return a; }else{ return b; } } int main() { printf("%d\n", max(10,12)); return 0; }
5 C语言宏定义 – 在编译阶段
#include
#define MATH_PI 3.14 //在编译阶段进行替换，因此在运行过程中很快
int main() { printf("%f\n", MATH_PI); return 0; }
6 C语言宏方法定义 – 在编译阶段，无类型
#include#define MAX(A,B) \ A>B?A:B int main() { printf("%d\n",MAX(20,10)); return 0; }
7 C语言条件判断
#includevoid test(int score){ if (score >= 90){ printf("优秀\n"); } else if (score >= 80) { printf("良好\n"); } else if (score >= 60) { printf("及格\n"); } else { printf("不及格\n"); } } void test1(int score){ switch (score/10) { case 9: puts("优秀"); break; case 8: puts("良好"); break; case 7: case 6: puts("及格"); break; default: puts("不及格"); break; } } int max(int a,int b){ return a>b?a:b; } int main() { test(88); test1(35); printf("%d", max(20,10)); return 0; }
8 C语言循环
#includeint main() { int i,j; for (i = 0; i < 100; i++){ printf("%d\n",i); } for (j = 0; j < 100 ; printf("%d\n",j++)) { puts("我先执行"); } int k = 0; while (k<100){ printf("%d\n",k); ++k; } int a = 0; do { printf("%d\n",a); a++; }while (a<100); return 0; }
一般情况，for循环用的最多，while用在死循环中。
9 C语言结构体 – 存储数据的集合 – 结构体的赋值，直接是内存的拷贝
#includestruct People{ int age; char* name; }; int main() { struct People p; p.age = 10; p.name = "yuxiang"; printf("age:%d\n",p.age); struct People p1 = p; //内存的拷贝 p.age = 20; printf("age:%d\n",p1.age); return 0; }
10 C语言结构体指针 - 同一块内存
#include#include struct People { int age; }; int main() { struct People *p = malloc(sizeof(struct People)); p->age = 10; printf("%d\n",p->age); struct People *p1 = p; //p1和p指向同一块内存 p1 -> age = 20; printf("%d\n",p1->age); free(p); return 0; }
11 C语言函数指针
#includevoid sayHello(){ printf("Hello C\n"); } int main() { // sayHello(); void (*p)(); //通过一个函数指针 p = sayHello; //指向sayHello方法 p(); //通过指针来执行方法 return 0; }
12 C语言typedef关键字
#includetypedef struct { int age; } People; typedef void (*Func)(); void sayHello(){ printf("type define function\n"); } int main() { People p; p.age = 10; printf("%d\n",p.age); Func f = sayHello; f(); return 0; }
13 C语言面向对象 – 思维方式
代码一：
typedef struct { int age; void (*sayHello)(); } People; void PeopleSayHello(){ printf("Hello\n"); } People * PeopleCreate(){ return malloc(sizeof(People)); } void PeopleDelete(People *p){ free(p); } People* PeopleInit(People* p,int age){ p->age = age; p->sayHello = PeopleSayHello; return p; } int main() { People *p = PeopleInit(PeopleCreate(),20); p->sayHello(); PeopleDelete(p); return 0; }
代码二：
#include
#include
//object begin>>>>>>>
#define ObjectField\
void(*onDelete)(void*);
typedef struct Object {
ObjectField
}Object;
#define ObjectCreate(TYPE) malloc(sizeof(TYPE))
#define ObjectDelete(obj) {\
obj->onDelete(obj);\
free(obj);\
}
void ObjectOnDelete(void *obj){
printf("Object on delete\n");
}
Object* ObjectInit(Object *obj){
obj->onDelete = ObjectOnDelete;
return obj;
}
//object end<<<<<<<<<
typedef struct {
ObjectField
int age;
void (*sayHello)();
} People;
void PeopleSayHello(){
printf("Hello\n");
}
void PeopleOnDelete(People *p){
ObjectOnDelete(p);
printf("People on delete\n");
}
People* PeopleInit(People* p,int age){
ObjectInit((Object*)p);
p->age = age;
p->sayHello = PeopleSayHello;
p->onDelete = PeopleOnDelete;
return p;
}
int main() {
People *p = PeopleInit(ObjectCreate(People),20);
p->sayHello();
ObjectDelete(p);
return 0;
}
14 C语言引入自定义头文件
//hello.h
#ifndef C13INCLUDE_HELLO_H //防止头文件重复引入
#define C13INCLUDE_HELLO_H
void sayHello();
#endif //C13INCLUDE_HELLO_H
// hello.c
#include
#include "hello.h" //自定义库
void sayHello(){
printf("Hello C");
}
//main.c
#include "hello.h"
int main() {
sayHello();
return 0;
}
15 C语言字符串操作 - sprintf
#include
#include
int main() {
char buf[100];
memset(buf,0,100);
sprintf(buf,"Hello %d,%f,%s",100,1.2,"yuxiang"); //将格式化的字符串打印到缓冲区中
printf("%s\n",buf);
return 0;
}
16 C语言文件操作 – fprintf、 fread
#include
int main() {
// int i;
// FILE *f = fopen("data.txt","w");
// if (f!=NULL) {
// for (i=0; i<100; i++){
// fprintf(f,"Hello %d\n",i);
// }
// }
// fclose(f);
FILE *f = fopen("data.txt","r");
fseek(f,0,SEEK_END);
long size = ftell(f);
char buf[size+1];
fseek(f,0,SEEK_SET);
fread(buf, sizeof(unsigned char),size,f);
buf[size] = '\0';
fclose(f);
printf("%s",buf);
return 0;
}
17 C语言实现猜数字小游戏
#include
#include
#include
int main() {
srand((int)time(NULL)); //使用当前系统的时间，指定一个随机的种子
int randNum = rand()%10;
printf("输入一个0到10的数值\n");
int userInput;
while (1){
scanf("%d",&userInput);
if (userInput
}else if (userInput>randNum) {
printf("数值过大\n");
}else{
printf("正确\n");
break;
}
}
printf("exit\n");
return 0;
}