#include<stdio.h>
int main(){
//一般都会在后面加
printf("hello world!
");
return 0;
}#include <stdio>
int main(){
int a,b,sum;
a = 99;
b = 99;
sum = a + b;
printf("sum = %d",sum);//%d 用来输出整数
}#include <stdio>
int main(){
char a = 'A';
a = a + 32; //一个大写的char字母加上32就会等于小写字母
printf("%c",a);//%c 用来输出char类型的字符
}#include <stdio>
int main(){
double a,b,sum;
a = 3.14;
b = 0.2;
sum = a + b;
printf("sum = %f
",sum);//%f用来输出小数
printf("sum = %d
", sum);//如果用%d来输出小数的话，则输出0
}#include<stdio.h>
int main() {
int a,b,avg;
scanf("%d%d",&a,&b);//scanf 相当于java的java.util.Scanner float用%f double用%lf
avg = (a + b)/2;
printf("avg = %d", avg);
}#include<stdio.h>
int main() {
char a,b;
a = getchar();
b = getchar();//从键盘键入一个字符
a += 3;
b += 3;
putchar(a);
putchar(b);//将字符输出到控制台
putchar('
');
return 0;
}
使用以上表中的数学函数时要在程序头加入 include <math.h>
#include<stdio.h>
/*
输入一个0到999的数字，输出各个位数
*/
int main() {
int a = 678;
int b = 678/100;
int c = (a-b*100)/10;
int d = (a-b*100-c*10);
printf("个位数为：%d
", d);
printf("十位数为：%d
", c);
printf("百位数为：%d
", b);
return 0;
}三目运算符：
#include<stdio.h>
int main() {
//输出大的那个数，用三目运算符
int a = 10;
int b = 90;
(a>b)?printf("%d",a):printf("%d",b);
}#include <stdio.h>
int main(){
// char str1[10];
// scanf("%s",str1);
// printf("%s",str1);
char str2[10],str3[10]; //使用上面的代码输入hello world时，屏幕只会输出hello,
scanf("%s",str2,str3); /*应该使用两个数组来接收，因为空格会被解析为 */
printf("%s %s",str2,str2);
}
#include <stdio.h>
int main(){
char str[20];
gets(str); //从键盘输入字符
puts(str); //如果输入的字符包含空格，也可以正常输出
}
int main(){
int a = 3;
int *i_pointer; //定义一个指针类型变量
i_pointer = &a; //指向整数a
printf("a: %d, i pointer: %d
",a,i_pointer); //打印地址
printf("a: %d, i pointer: %d
",a,*i_pointer); //打指针所以指的对象
*i_pointer = 4; //相当于 a = 4
printf("a: %d, i pointer: %d
",a,i_pointer);
printf("a: %d, i pointer: %d
",a,*i_pointer);
}#include <stdio.h>
int main(){
int *p1,*p2,a,b; //定义两个指针变量，两个int变量
printf("please enter two integer number:
");
scanf("%d%d",&a,&b); //从键盘输入 a 和 b
p1 = &a; //p1指向a
p2 = &b; //p2指向b
if(a<b){ //如果a<b交换指针地址
p1 = &b;
p2 = &a;
}
printf("a= %d, b= %d
",a,b); //输出a和b的值不变
printf("max= %d, min= %d",*p1,*p2); //p1和p2和值对换了
}
自定义类型：
#include <stdio.h>
int main(){
struct Student{
int No;
char name[10];
double source;
} cai = {1,"chaijunwei",99.9};
printf("No: %d
name:%s
source:%f
",cai.No,cai.name,cai.source);
Student cai2 = {1,"cai2",99.9};
printf("No: %d
name:%s
source:%f",cai2.No,cai2.name,cai2.source);
}
自定义类型的数组：
#include <stdio.h>
int main(){
struct Student{
int No;
char name[10];
double source;
};
Student students[2] = {
{1,"chai1",80},
{2,"chai2",99},
};
int i = 0;
for(;i < 2; i ++){
printf("%s",students[i].name);
}
return 1;
}
自定义的类型，用指针传递，用->符号：
#include <stdio.h>#include <stdio.h>
//自定义一个Book类型
struct Book{
int id;
char name[10];
};
//声明函数
void printBook(struct Book *book);
int main(){
struct Book book = {1,"java"};
printBook(&book);//将book的内存地址传入方法
}
void printBook(struct Book *book){
printf("bookName: %s",book->name);//使用->来获得属性值
}链表：
#include <stdio.h>
struct LinkeList{
int element;
struct LinkeList *next;
};
int main(){
struct LinkeList *first,node1,node2,node3;
node1.element = 1;
node2.element = 2;
node3.element = 3;
first = &node1;
node1.next = &node2;
node2.next = &node3;
node3.next = NULL;
do{
printf("%d
",first->element);
first = first->next;
}
while(first != NULL);
return 0;
}共用体类型：
#include <stdio.h>
//定义一个共用体类型
union Cate{
int clas;
char name[10];
};
//可能是学生也可能是老师，如果是学生就输入clas,如果是老师就输入name
struct Person{
char job[10];
union Cate cate;
};
int main(){
struct Person person1;
scanf("%s",person1.job);
if(person1.job[0] == 's'){
scanf("%d",&person1.cate.clas);
printf("job: %s
class: %d",person1.job,person1.cate.clas);
}else if(person1.job[0] == 't'){
scanf("%s",person1.cate.name);
printf("job: %s
class: %s",person1.job,person1.cate.name);
}
}typedef:
