1.第一个C语言程序.cpp
/*
这是第一个C语言程序
*/
#include<stdio.h>//头文件 std标准 io输入输出
int main(){//主函数--程序的入口main
//int--->返回值
printf("Hello!");//输出语句，表示打印Hello
return 0;//返回一个0,表示正常结束；异常结束返回一个
//非0值
}
2.两个整数求和.cpp
#include<stdio.h>
int main(){
//程序-->内存 --->执行
int a,b,sum;//定义变量,在内存中分配空间
a = 100;
b = 30;//给变量赋值
sum = a+b;
printf("你好sum=%d\n",sum);
//"sum=%d\n"输出格式
//sum输出的变量 %d表示输出一个整数
//\n回车换行
printf("hello");
return 0;
}
3.常量.cpp
#include<stdio.h>
int main(){
//1.整型常量 -100 1000 0
int a = 100;
printf("a=%d\n",a);
//2.实型常量2.5 34.67
float b = 12.3;//单精度浮点型
printf("b=%f\n",b);
float c= 12.5e3;//12.5乘以10的3次方
//e或E都可以
printf("c=%f\n",c);
float d = 2.3e-2;//2.3乘以10的-2次方
printf("d = %f\n",d);
//3.字符常量
char e = '?';
printf("e = %c\n",e);
//转义字符
char f= '\n';//回车换行
printf("f = %c\n",f);
printf("hel\thello\n");
printf("\c");
char g ='\110';//八进制对应的字符 65
printf("g = %c\n",g);
char h='\x41'; //十六进制对应的字符
printf("h = %c\n",h);
//4.字符串常量
char i[] = "abcd";
printf("i=%s\n",i);
//'a' "a"
return 0;
}
5.变量.cpp
#include<stdio.h>
int main(){
int a;//定义变量，在内存中开辟4Byte大小
a = 10;//给变量赋值
//1Byte = 8bit
//4Byte = 32bit
//00000000 00000000 00000000 00000000
//11111111 11111111 11111111 11111111
//01111111 11111111 11111111 11111111
//1111=+7
//0111=-7
printf("a=%d\n",a);
short b = 12;//短整型，在内存中开辟2Byte
printf("b=%d\n",b);
long c = 13;//长整型，内存中开辟4Byte
printf("c=%d\n",c);
long long d = 13;//双长型， 内存中开辟8Byte
printf("d=%d\n",d);
return 0;
}
6.无符号数.cpp
#include<stdio.h>
int main(){
//补码
unsigned int a = 100;
//11111111 11111111 11111111 11111111
//00000000 00000000 00000000 00000000
//1111=15
//0000=0
printf("a = %d\n",a);
unsigned int b = -100;
printf("b = %d\n",b);
printf("b = %u\n",b);//%u无符号数的输出格式
//0110
return 0;
}
7.字符型.cpp
#include<stdio.h>
int main(){
char ch = 'a';//会在内存中开辟1Byte。
//字符在计算机存储的时候，存储的都是字符的ASCII码
printf("ch = %c\n",ch);
printf("ch ascii = %d\n",ch);
//计算'1'-1的结果？ 48
char ch2 = '1';
int a = 1;
printf("%d\n",(ch2-a));
return 0;
}
8.字符转化.cpp
#include<stdio.h>
int main(){
char ch = 'a';//97 A:65 =32
//小写字符的ascii码和大写字符的ascii码相差32
char ch2 = ch - 32;
printf("ch2 = %c",ch2);
return 0;
}
9.浮点数.cpp
#include<stdio.h>
int main(){
float a = 12.34519872123F;
printf("a = %.8f\n",a);
double b = 12.34519872123;
printf("b = %.11f\n",b);
//12.4--double 12.4f--float
float c = 12.3456;
//将double的数赋值给float类型，有可能发生数据溢出
return 0;
}
10.算术运算.cpp
#include<stdio.h>
int main(){
int a = 17;
int b = 5;
int c;
c = a+b; //=赋值运算符 +算术运算符
//算术运算符的优先级高于赋值运算符
printf("c= %d\n",c);
c = a-b;
printf("c= %d\n",c);
c = a*b;
printf("c= %d\n",c);
c = a/b;//17/5 = 3 int/int=int
printf("c= %d\n",c);
c = a%b;//2.3%2
printf("c= %d\n",c);
//%两边的值，必须是整型
//printf("c= %d\n",2.3%2.3);错误
return 0;
}
11.++.cpp
#include<stdio.h>
int main(){
int a = 18 ;
printf("a=%d\n",a++);//1.打印 2.++
printf("a=%d",a);
return 0;
}
12.不同类型的运算.cpp
#include<stdio.h>
int main(){
int i = 3;
float f = 3.5f;
double d = 7.5;
double dd;//从左到右
//1.计算10+'a'=107;107+i*f-d/3
//2. i*f=10.5;107+10.5-d/3
//3.107+10.5=117.5;117.5-d/3
//4.d/3=7.5/3=2.5;117.5-2.5
//5.115.000000
printf("dd=%f",dd);
return 0;
}
13.强制类型转化.cpp
#include<stdio.h>
int main(){
float a = 12.8456f;
int b;
b = (int)a;
printf("b = %d",b);
return 0;
//(int)((double)(7/2)+3.5)
//1.(int)((double)3+3.5)
//2.(int)(3.0+3.5)
//3.(int)6.5
//4.6
//(int)((double)7/2+3.5)
}
14.求素数.cpp
#include<stdio.h>
int main(){
//求100-200之间所有的素数。
int flag = 0;//0表示素数 1表示不是素数
for(int i=100;i<=200;i++){//101
flag = 0;
for(int j = 2;j<=i-1;j++){
if(i%j==0){
flag=1;
}
}
if(flag==0) printf("%5d",i);
}
return 0;
}
15.科学表示.cpp
#include<stdio.h>
int main(){
printf("%-20.15e",10.0/3);
return 0;
}
17.printf用法.cpp
#include<stdio.h>
int main(){
//1.d格式--->输出整型数据
printf("No.1:%d\n",122);
printf("No.2:%5d\n",122);//输出数据占5列（向右对齐）
printf("No.3:%-5d\n",122);//输出数据占5列（向左对齐）
//2.c格式--->单个字符
printf("No.4:%c\n",'\101');
//3.f格式--->浮点型数据（float,double）
printf("No.5:%f\n",3.14);//3.140000
float a = 10.0f;
printf("No.6:%20.15f\n",a/3);//占20列，15位小数
printf("No.7:%-20.15f\n",a/3);
//4.e格式--->结果为指数形式
printf("No.8:%25.15e\n",a/3);
printf("No.9:%e\n",190.34);
printf("No.10:%e\n",0.002345);
//5.o格式-- >将一个数按照8进制输出
printf("No.11:%o\n",1001);
//6.x格式-- >将一个数按照16进制输出
printf("No.12:%x\n",1001);
//7.u格式-->输出一个无符号的数
printf("No.13:%u\n",1001);
return 0;
}
18.scanf.cpp
#include<stdio.h>
int main(){
int a;
scanf("a=%d",&a); //输入格式,往什么地方输入
//&-->取地址符
printf("a = %d\n",a);
printf("a(addr)=%p\n",&a);
printf("a(addr)=%d\n",&a);
return 0;
}
18.scanf2.cpp
#include<stdio.h>
int main(){
float a,b,c;
scanf("a=%f,b=%f,c=%f",&a,&b,&c);
printf("a=%f,b=%f,c=%f",a,b,c);
return 0;
}
18.scanf3.cpp
#include<stdio.h>
int main(){
int a,b,c;
scanf("%d%d,%d",&a,&b,&c);
printf("a=%d,b=%d,c=%d",a,b,c);
//1.每输入一个数据后，加空格
//2.每输入一个数据后，加回车
//3. 每输入一个数据后，加tab
return 0;
}
18.scanf4.cpp
#include<stdio.h>
int main(){
char a,b,c;
scanf("%c%c%c",&a,&b,&c);
printf("a=%c,b=%c,c=%c",a,b,c);
//对于字符输入时，每一个字符要紧紧的挨在一起。
return 0;
}
19.putchar.cpp
#include<stdio.h>
int main(){
char a = 'a';
char b = 'r';
char c = 'w';
int d = 65;
putchar(a); //将变量a的值输出
putchar('\n');
putchar(b);
putchar(c);
putchar('\101');
putchar(d);
return 0;
}
20.getchar.cpp
#include<stdio.h>
int main(){
char a,b,c;
a = getchar();//获得到键盘输入的单个字符
b = getchar();
c = getchar();
putchar(a);
putchar(b);
putchar(c);
return 0;
}
21.例题.cpp
#include<stdio.h>
int main(){
int x,y;
scanf("%d%3d",&x,&y);
printf("%d %d",x,y);
return 0;
}
22.三角形面积.cpp
#include<stdio.h>
#include<math.h>
int main(){
//求三角形面积
//海伦公式
double a,b,c;//三个边长
printf("请输出三个边的边长：\n");
scanf("a=%lf,b=%lf,c=%lf",&a,&b,&c);
double s,area;
s = (a+b+c)/2;
area = sqrt(s*(s-a)*(s-b)*(s-c));//sqrt(3)
printf("三角形的面积是：%f",area);
return 0;
}
23.求根.cpp
#include<stdio.h>
#include<math.h>
int main(){
float a,b,c;
printf("请输入a,b,c的值：\n");
scanf("%f,%f,%f",&a,&b,&c);
float p,q;
p = -b/(2.0*a);
q = sqrt(b*b-4*a*c)/2.0*a;
float x1,x2;
x1 = p+q;
x2 = p-q;
printf("x1=%f,x2=%f",x1,x2);
return 0;
}
24.关系运算.cpp
#include<stdio.h>
int main(){
printf("%d\n",1>2);
printf("%d\n",100>2);
printf("%d\n",100!=2);
printf("%d\n",100>=2);
return 0;
}
25.关系运算优先级.cpp
#include<stdio.h>
int main(){
int a =1,b=3,c=2;
printf("%d\n",(a==b>c));
//1.b>c 3>2=1
//2.a==1
printf("%d\n",(a<=b==c));
printf("%d\n",(a+1>b==c));
//1.a+1
//2.2>b-->0
//3.0==c
return 0;
}
26.逻辑运算符.cpp
#include<stdio.h>
int main(){
printf("%d\n",(1&&1));
printf("%d\n",(1&&0));
printf("%d\n",(0&&1));
printf("%d\n",(0&&0));
printf("%d\n",(1||1));
printf("%d\n",(1||0));
printf("%d\n",(0||1));
printf("%d\n",(0||0));
printf("%d\n",(!0));
printf("%d\n",(!1));
return 0;
}
27.逻辑运算符2.cpp
#include<stdio.h>
int main(){
int a = 10;
int b = -2;
printf("%d",(a&&b));
//非0的数表示真,0表示假
return 0;
}
28.逻辑运算符3.cpp
#include<stdio.h>
int main(){
int a = 2,b=4,c=3,d=7;
printf("%d\n",a<b||c<d);//1||1--->1
printf("%d\n",a<b&&c<d);//1
printf("%d\n",a>b||c<d);//0||1--->1
printf("%d\n",a<b&&c>d);//1&&0--->0
printf("%d\n",!a<b&&c>d);//0<4&&c>d-->0
return 0;
}
29.练习.cpp
#include<stdio.h>
int main(){
int a = 1,b=9;
a++||(b = b+100);//2||?=1
printf("b=%d",b);
return 0;
}
30.if.else.cpp
#include<stdio.h>
int main(){
//例如：输入两个整数，由大到小输出。
int a,b,t;
scanf("%d%d",&a,&b);//12 6 6 12
if(a<b){
t = a;
a = b;
b = t;
}
printf("%d,%d",a,b);
return 0;
}
32.闰年.cpp
#include<stdio.h>
int main(){
int year;
printf("请输入年份：\n");
scanf("%d",&year);
if((year%4==0&&year%100!=0)||(year%400==0))
printf("是闰年！");
else
printf("不是闰年！");
return 0;
}
33.分段函数.cpp
#include<stdio.h>
int main(){
double x,y;
scanf("%lf",&x);
if(x<1){
y = x;
}else if(1<=x&&x<10){
y=2*x-1;
}else if(x>=10){
y = 3*x-11;
}
printf("y = %f",y);
return 0;
}
//if(){}
//if(){}else{}
//if(){}else if(){}else if(){}...else{}
34.求最大值.cpp
#include<stdio.h>
int main(){
int a ,b,max;
scanf("%d%d",&a,&b);
// //方法1
// if(a>b)
// max = a;
// else
// max = b;
// printf("max= %d",max);
//方法2
// max = (a>b)?a:b;
// printf("max= %d",max);
//方法3
// (a>b)?max = a:max = b;
// printf("max= %d",max);
//方法4
a>b?printf("max=%d",a):printf("max=%d",b);
return 0;
}
//输入一个字符，判断它是否是大写字母，如果是大写字母
//转换为小写字母，如果是小写字母，直接输出。
35.大小写转换.cpp
#include<stdio.h>
//输入一个字符，判断它是否是大写字母，如果是大写字母
//转换为小写字母，如果是小写字母，直接输出。
int main(){
char ch,c;
ch=getchar();
c=(ch>='A'&&ch<='Z')?ch+32:ch;
putchar(c);
return 0;
}
36.switch.cpp
#include<stdio.h>
int main(){
//用户输入成绩的等级，显示用户的分数
//A-->85分以上,B->70-84,C->60-69,D->60以下
char grade;
scanf("%c",&grade);
switch(grade){
case 'A':printf("85分以上");//break跳出
case 'B':printf("70-84");break;
case 'C':printf("60-69");
case 'D':printf("60以下");break;
default:printf("输入错误！");
}
//当程序碰到一个匹配的case后 ，会从当前语句开始依次执行
//直到碰到break语句或switch语句执行完。
return 0;
}
37.一元二次方程.cpp
#include<stdio.h>
#include<math.h>
int main(){
double a,b,c,disc,x1,x2,p,q; //-0.00000001
printf("请输入abc的值\n");
scanf("%lf%lf%lf",&a,&b,&c);
if(fabs(a)<=1e-6){//a==0
printf("不是一元二次方程\n");
}else{
disc=b*b-4*a*c;
if(fabs(disc)<=1e-6){//disc==0
printf("两个相等的实数根:%f\n",(-b/(2*a)));
}else if(disc>1e-6){//1 2 2
x1 = (-b+sqrt(disc))/(2*a);
x2 = (-b-sqrt(disc))/(2*a);
printf("no1:%f,no2:%f",x1,x2);
}else{
p = -b/(2*a);//实数
q = sqrt(-disc)/(2*a);//虚数
printf("no1:%8.4f+%8.4fi\n",p,q);
printf("no2:%8.4f-%8.4fi\n",p,q);
}
}
return 0;
}
38.while循环.cpp
#include<stdio.h>
int main(){
//1+2+3+...+100
int i = 1;
int sum = 0;
while(i<=100){
sum = sum+i;
i++;
}
printf("sum=%d\n",sum);
printf("i=%d\n",i);
//1.i=1 sum=0 i<=100(ok) sum =0+1=1 i=2
//2.i<=100(ok) sum = 1+2=3 i=3
//3.i<=100(ok) sum = 3+3=6 i=4
//4.i<=100(ok) sum = 6+4=10 i=5
//....
//100.i<=100(ok) sum =4950 +100=5050 i=101
//101.i<=100(false) 跳出循环
return 0;
}
39.do..while.cpp
#include<stdio.h>
int main(){
//1+2+3+...+100
int i =1;
int sum = 0;
do{
sum+=i;//sum = sum+i
i++;
}while(i<=100);
printf("sum=%d",sum);
return 0;
}
40.while、.cpp
#include<stdio.h>
int main(){
int i = 1;
int a = 0;
while(i<1){
a = 100;
i++;
}
printf("a = %d",a);
return 0;
}
41.do..while、.cpp
#include<stdio.h>
int main(){
int i = 1;
int a = 0;
do{
a = 100;
i++;
}
while(i<1);
printf("a = %d",a);
return 0;
}
42.for循环.cpp
#include<stdio.h>
int main(){
//1+2+3...+100
int sum = 0;
for(int i=1;i<=100;i++){
sum = sum +i;
}
printf("sum = %d",sum);
return 0;
}
43.break.cpp
#include<stdio.h>
int main(){
for(int i=1;i<=10;i++){
if(i%5==0) continue;
printf("%d\t",i);
}
//1.1
//2.2
//3.3
//4.4
//5.这一次循环不执行
//6. 6
//7.7
//8.8
//9.9
//10.这一次循环不执行
return 0;
}
44.不能被3整除.cpp
#include<stdio.h>
int main(){
for(int i=100;i<=200;i++){
if(i%3==0) continue;
printf("%d\n",i);
}
return 0;
}
45.被7整除.cpp
#include<stdio.h>
int main(){
int i,j;
for(i=100,j=0;i<=200;i++)
if(i%7==0){
printf("%4d",i);
j++;
if(j%5==0) printf("\n");
}
return 0;
}
46.两层循环.cpp
#include<stdio.h>
int main(){
int i;//行
int j;//列
for(i=1;i<=4;i++){//行
for(j=1;j<=5;j++){//列
printf("%6d",i*j);
}
printf("\n");
}
return 0;
}
47.水仙花.cpp
#include<stdio.h>
int main(){//234/100=2 345/100=3 6789/1000
int b,s,g;//百 十 个
for(int i=100;i<=500;i++){
b=i/100;
s=i%100/10;
g=i%10;
if(i==b*b*b+s*s*s+g*g*g) printf("%d是水仙花数",i);
}
return 0;
}
48.求pi.cpp
#include<stdio.h>
#include<math.h>
int main(){
int sigin = 1;// 分子
double n = 1 ;//分母
double pi =0.0; //pi值
double term = 1.0; //每一项
while(fabs(term)>=1e-8){
pi = pi +term;
n = n +2;
sigin = -sigin;
term=sigin/n;
}
pi = 4*pi;
printf("%.18f",pi);
return 0;
}
49.数组.cpp
#include<stdio.h>
int main(){
int a[10];//[常量]
//1.定义了一个整型int数组。在这个数组中，每一个元素
//都是int类型。
//2.a表示数组名称,表示数组首元素的地址,并且这个地址为常量
//3.10表示数组中有10个int类型的元素，数组中第一个元素的
//下标为0.
//4.会在内存中开辟连续的10个空间存放int类型的元素。
a[0] = 5; //0-->下标
a[1] = 10;
a[2] = 11;
//a[6] = 0;
printf("%d\n",a);//a[0]元素的地址12345
printf("%d\n",a[0]);
printf("%d\n",a+1);//a[1]元素的地址12349
printf("%d\n",a+2);//a[2]元素的地址
for(int i=0;i<=9;i++){
printf("%d\t",a[i]);
}
printf("\n");
for(int i=0;i<=9;i++){
printf("%d\n",a+i);
}
return 0;
}
50.数组基本形式.cpp
#include<stdio.h>
int main(){
//c#
//1.
int a[10]={1,2,3,4,5,6,7,8,9,0};
for(int i=0;i<=9;i++){
printf("%d\t",a[i]);
}
printf("\n");
//2.
int b[10]={1,2,3,4};
for(int i=0;i<=9;i++){
printf("%d\t",b[i]);
}
printf("\n");
//3.
int c[10] = {0};
for(int i=0;i<=9;i++){
printf("%d\t",c[i]);
}
printf("\n");
//4.
int d[] = {1,2,3,6,7,8};
for(int i=0;i<=5;i++){
printf("%d\t",d[i]);
}
printf("\n");
int j = 10;
int array[j];
return 0;
}
51.斐波那契数列.cpp
#include<stdio.h>
int main(){
//斐波那契数列fibonacci
//1 1 2 3 5 8 13...
//用数组求解fibonacci的前20项
int f[20]={1,1};
for(int i=2;i<=19;i++){
f[i] = f[i-2]+f[i-1];
}
for(int i=0;i<=19;i++){
if(i%5==0) printf("\n");
printf("%d\t",f[i]);
}
return 0;
}
52.二维数组.cpp
#include<stdio.h>
int main(){
int a[5][5];//行 列
//1.定义了一个整型二维数组,数组中的每一个元素都为
//整型int元素
//2.数组有5行5列，a表示首行元素的地址
//3.二维数组的行、列下标都是从0开始的。
//4.数组的每一个元素在内存中是按行顺序存放的
a[0][0] = 100;
printf("%d\n",a[0][0]);
printf("%d\n",a);//第一行元素的地址6487472
printf("%d\n",a+1);//第二行元素的地址6487492
printf("%d\n",a[0]);//第一个元素a[0][0]的地址
printf("%d\n",a[0]+1);//第二个元素a[0][1]的地址
printf("%d\n",a[1]+1);//第二行第二列a[1][1]的地址
return 0;
}
53.二维数组赋值.cpp
#include<stdio.h>
int main(){
//1.
int a[3][4] = {{1,2,3,4},{5,6,7,8},{9,0,1,2}};
printf("%d\n",a[2][1]);
for(int i=0;i<=2;i++){//行
for(int j=0;j<=3;j++){//列
printf("%d\t",a[i][j]);
}
printf("\n");
}
//2.
int b[3][4] = {1,2,3,4,5,6,7,8,9,0,1,2};
for(int i=0;i<=2;i++){//行
for(int j=0;j<=3;j++){//列
printf("%d\t",b[i][j]);
}
printf("\n");
}
//3.
int c[3][4]={{1,2},{2},{4}};
for(int i=0;i<=2;i++){//行
for(int j=0;j<=3;j++){//列
printf("%d\t",c[i][j]);
}
printf("\n");
}
//4.
int d[3][4]={0};
for(int i=0;i<=2;i++){//行
for(int j=0;j<=3;j++){//列
printf("%d\t",d[i][j]);
}
printf("\n");
}
//5.
int e[][4]={1,2,3,4,5,6,7,8,9,10,11,12};
//int e[3][]={1,2,3,4,5,6,7,8,9,10,11,12};错误！
//int e[][]={1,2,3,4,5,6,7,8,9,10,11,12};错误！
for(int i=0;i<=2;i++){
for(int j=0;j<=3;j++){
printf("%5d",e[i][j]);
}
printf("\n");
}
return 0;
}
54.数组例题.cpp
#include<stdio.h>
int main(){
int a[10];
//1.输入10个数
// for(int i=0;i<=9;i++){//&a[0]
// scanf("%d",&a[i]);
// }
for(int i=0;i<=9;i++){//a+1
scanf("%d",a+i);
}
//2.求平均分
float avg,sum = 0;
for(int i=0;i<=9;i++){
sum = sum +a[i];
}
avg = sum/10;
//3.统计比平均分少的个数
int j = 0;
for(int i=0;i<=9;i++){
if(avg>a[i]) j++;
}
printf("%d,%f",j,avg);
return 0;
}
55.字符数组.cpp
#include<stdio.h>
int main(){
//1.字符数组
char a[10] = {'I',' ','l','o','v','e'};
for(int i=0;i<=9;i++){
printf("%c\n",a[i]);
}
//2.
char b[]={"hello"};//字符串
//字符串b在内存中占了多少空间？6Byte
//字符串b的有效字符数为？5
printf("%d\n",sizeof(b)); //
for(int i=0;i<=5;i++){
printf("%c",b[i]);
}
printf("\n",b);
printf("%s\n",b);
//3.
char c[] = "hellohello";
printf("%s",c);
return 0;
}
56.字符串.cpp
#include<stdio.h>
int main(){
char a[] = "helloworld!";//\0
printf("%s\n",a);
a[5] = '\0';
printf("%s",a);
// for(int i=0;a[i]!='\0';i++){
// printf("%c",a[i]);
// }
return 0;
}
57.字符串的输入.cpp
#include<stdio.h>
int main(){
char str1[5],str2[5],str3[5];
//str1
scanf("%s%s%s",str1,str2,str3);
printf("str1=%s,str2=%s,str3=%s",str1,str2,str3);
//输入方式1：she he she
//输入方式2：she he she
//输入方式3：she回车he回车she
return 0;
}
58.字符串操作函数.cpp
#include<stdio.h>
#include<string.h>
int main(){//string---字符串
char str1[] ="I love china!";
//1.输出字符串
puts(str1); //同printf("%s",str1);
//2.输入一个字符串
// char str2[10];
// gets(str2);
// puts(str2);
//3.字符串连接函数strcat(字符串1,字符串2);
//功能：将字符串2，拼接到字符串1中。
char str3[] = "hello";
char str4[] = "world";
strcat(str3,str4);//
puts(str3);
puts(str4);
//4.字符串的复制strcpy(字符串1,字符串2)
//功能：将字符串2复制到字符串1中。
char str5[10];
char str6[]="hello";
strcpy(str5,str6);
puts(str5);
//str5=str6;
//5.字符串比较函数strcmp(字符串1,字符串2)
//两个字符串相等，返回0;
//字符串1<字符串2,返回-1；
//字符串1>字符串2,返回1；
//1.按照字典的顺序比较大小的，越往后越大
//2.小写字母>大写字母 a>A
//3.如果出现不同的字符串，以第一个不同的字符比较为准
char str7[] ="helloa";
char str8[]="hellob";
printf("%d\n",strcmp(str7,str8));
//6.检查字符串的实际长度strlen()
char str9[] = "hello";//5
printf("%d\n",strlen(str9));//实际长度？
printf("%d\n",sizeof(str9));//占多大空间？
//7.将字符串转换为小写strlwr() lowercase
char str10[] ="BBBB";
strlwr(str10);
puts(str10);
//8.将字符串转换为大写 strupr() upercase
strupr(str10);
puts(str10);
return 0;
}
59.二维数组例题.cpp
#include<stdio.h>
int main(){
//1.定义二维数组
int a[4][4] = {{23,44,12,77},{13,2,33,12}
,{23,45,12,65},{11,9,15,78}};
//2.定义需要的变量
int sum = 0;
//3.算法---- 遍历
for(int i=0;i<=3;i++){
for(int j=0;j<=3;j++){
if(a[i][j]>max) {
max = a[i][j];
x = i;
y = j;
}
}
}
printf("max=%d,i=%d,j=%d",max,x,y);
return 0;
}
60.二维数组例题2.cpp
#include<stdio.h>
int main(){
int a[10][10]={0};
for(int i=0;i<=9;i++){
a[i][0] = 1;
a[i][i] = 1;
}
for(int i=2;i<=9;i++){
for(int j=1;j<=9;j++){
a[i][j] = a[i-1][j-1]+a[i-1][j];
}
}
for(int i=0;i<=9;i++){
for(int j=0;j<=i;j++){
printf("%5d",a[i][j]);
}
printf("\n");
}
return 0;
}
61.最大公约数.cpp
#include<stdio.h>
int main(){
printf("请输入两个值\n");
int m;
int n;
scanf("%d%d",&m,&n);
//1.找m和n最小的那个数
int temp;//保存最小的那个数
if(m>n) temp =n;
else temp =m;
//2.从最小值开始除，直到m和n第一次被同时整除，跳出循环
int i;
for(i = temp;i>0;i--){
if(m%i==0&&n%i==0){
printf("最大公约数为：%d\n",i); break;
}
}
int lcm;//
lcm = m * n /i;
printf("最小公倍数为：%d\n",lcm);
return 0;
}
62.求素数.cpp
#include<stdio.h>
int main(){
int n;//要判断的这个数
scanf("%d",&n);
int i;
for(i=2;i<=n-1;i++){
if(n%i==0) break;
}
//n=5
//i=2 2<=4 (ok) 5%2
//i=3 3<=4(ok) 5%3
//i=4 4<=4(ok) 5%4
//i=5
if(i<n) printf("不是素数\n");
else printf("是素数\n");
return 0;
//求100-200之间所有的素数。
}
63.函数.cpp
#include<stdio.h>
int main(){
//2.函数的声明--告诉编译器，定义了一个函数
void print_info();
//3.使用函数（调用函数）
print_info();
print_info();
return 0;
}
//1.定义自定义函数
void print_info(){//void返回值(空) print_info函数名称
//()无参的函数
printf("hello world!\n");//函数的操作
}
64.函数2.cpp
#include<stdio.h>
//1.定义自定义函数
void print_info(){//void返回值(空) print_info函数名称
//()无参的函数
printf("hello world!\n");//函数的操作
}
int main(){
//2.使用函数（调用函数）
print_info();
print_info();
return 0;
}
65.函数.cpp
#include<stdio.h>
int main(){
void print_info();
int sum(int,int);//int sum(int a,int b);
print_info();
int x =3;
int y = 4;
int s = sum(x,y);//实参 （实际参数）
printf("s = %d",s);
return 0;
}
void print_info(){
printf("hello world!\n");
}
//求两个整数的和
//形参
int sum(int a,int b){//函数执行完后，会带出int类型的值。
int c = a+b;
return c;
}
66.函数例题.cpp
#include<stdio.h>
int main(){
int max(int,int);
printf("请输入两个整数\n");
int a,b;
scanf("%d%d",&a,&b);
int s = max(a,b);
printf("s = %d",s);
return 0;
}
int max(int a,int b){
int z;
if(a>b){
z = a;
}else{
z = b;
}
return z;
}
67.函数例题2.cpp
#include<stdio.h>
int main(){
void fun(int);
int a = 1;
fun(a);
printf("%d",a);
return 0;
}
void fun(int a){
a = 100;
}
68.函数例题3.cpp
#include<stdio.h>
int main(){
float max(float a,float b);
float a,b;
scanf("%f%f",&a,&b);
int s = max(a,b);
printf("%d",s);
return 0;
}
int max(float a,float b){
return a>b?a:b;
}
69.函数嵌套.cpp
#include<stdio.h>
int main(){
int max4(int,int,int,int);//1
int a=1,b=4,c=20,d=13;//2
int max = max4(a,b,c,d);//3
printf("max = %d",max);//19
return 0;//20
}
int max4(int a,int b,int c,int d){//4
int max2(int,int);//声明 5
int m = max2(a,b);//6
m = max2(m,c);//10
m = max2(m,d);//14
return m;//18
}
int max2(int a,int b){//7 11 15
if(a>b) return a;//8 12 16
else return b;//9 13 17
}
70.函数递归.cpp
#include<stdio.h>
int main(){
//5! = 5*4*3*2*1
int n = 1;
for(int i=1;i<=5;i++){
n = n * i;
}
printf("%d",n);
return 0;
}
71.函数递归2.cpp
#include<stdio.h>
int main(){
int fun(int n);
int s = fun(5);
printf("%d",s);
return 0;
}
int fun(int n){
int f;
if(n==1||n==0){
f = 1;
}else if(n>=2){
f = fun(n-1)*n;
}
return f;
}
72.函数递归3.cpp
//1+2+3+....+100
#include<stdio.h>
int main(){
int age(int n);
int age1 = age(5);
printf("age = %d",age1);
return 0;
}
int age(int n){
if(n==1) return 10;
else return age(n-1)+2;
}
73.函数递归4.cpp
//1+2+3+....+100 sum()
//sum(100)=sum(99)+100
//sum(99)=sum(98)+99
//sum(n)=sum(n-1)+n
//sum(1)=1
#include<stdio.h>
int main(){
int sum(int n);
int sum1 = sum(100);
printf("%d",sum1);
return 0;
}
int sum(int n){
if(n==1) return 1;
else return sum(n-1)+n;
}
74.函数递归5.cpp
#include<stdio.h>
int main(){
int apple(int n,int k);
int s = apple(3,5);
printf("%d",s);
return 0;
}
int apple(int n,int k){//表示n的k次方
if(k==0) return 1;
else return apple(n,k-1)*n;
}
75.函数数组.cpp
#include<stdio.h>
int main(){
int com(int,int);
int a[10] = {2,6,10,4,8,30,14,19,20,11};
int max = a[0];//a a+2 &a[4]
int i = 0;
for(int j=1;j<=9;j++){
if(com(max,a[j])>max) {
max = com(max,a[j]);
i = j;} }
printf("max = %d,index = %d",max,i);
return 0;
}
int com(int a,int b){
if(a>b) return a;
else return b;
}
76.数组名作为函数形参.cpp
#include<stdio.h>
int main(){
void fun(int[]);
int a[5] ={1,2,3,4,5};
for(int i=0;i<=4;i++){
printf("%5d",a[i]);
}
printf("\n");
fun(&a[0]);//a
for(int i=0;i<=4;i++){
printf("%5d",a[i]);
}
return 0;
}//引用传递
void fun(int b[]){//int b[]--->只能接收地址
b[4] = 100;
}
77.数组名作为函数形参2.cpp
#include<stdio.h>
int main(){
void fun1(int);
void fun2(int[]);
int x = 10;
fun1(x);//单向传递的值
printf("x = %d\n",x);
int y = 10;
fun2(&y);//单向传递的地址
printf("y = %d\n",y);
return 0;
}
void fun1(int a){
a = 100;
}
void fun2(int a[]){
a[0] = 100;
}
78.局部变量.cpp
#include<stdio.h>
int main(){
//.....
int a=1,b=2,c=6;
printf("a=%d,b=%d,c=%d",a,b,c);
return 0;
}
int fun(int a){
//....
int b;
int c;
}
79.局部变量2.cpp
#include<stdio.h>
int main(){
int i =10;
for(i=0;i<=10;i++){
printf("%d\n",i);
}
printf("%d\n",i);
return 0;
}
80.全局变量.cpp
#include<stdio.h>
int P = 1,Q =10;
void fun1(){
int P=100,Q=100;
printf("P=%d,Q=%d\n",P,Q);
}
int A= 4,B =10;
void fun2(){
printf("A=%d,B=%d\n",A,B);
}
int main(){
fun1();
fun2();
printf("P=%d,Q=%d\n",P,Q);
return 0;
}
81.真题1.cpp
#include<stdio.h>
#include<math.h>
int main(){
double Fun2(double error);
double s = Fun2(1e-6);
printf("%.16f",s);
return 0;
}
double Fun2(double error){//Fun2(1e-6)
int sign = 1;//分子
double n = 1.0;//分母
double term = 1.0;// 分子/分母
double pi = 0;
while(fabs(term)>=error) {
pi = pi +term;
sign = -sign;
n = n +2;
term = sign/n;
}
pi = 4*pi;
return pi;
}
82.真题2.cpp
#include<stdio.h>
int main(){
float a = 2;//分子
float b = 1;//分母
float sum = 0.0f;//和
for(int i=1;i<=20;i++){
sum = sum+a/b;
a = a+b;//新的分子
b = a-b;//新的分母
}
printf("%f",sum);
//1.sum = 0+2/1 a = 3 b =2
//2.sum = 0+2/1+3/2 a=5 b=3
//3.sum = 0+2/1+3/2+5/3
return 0;
}
83.真题3.cpp
#include<stdio.h>
int main(){
float a[20];//分子
a[0] = 2;a[1] = 3;
for(int i=2;i<=19;i++){
a[i] = a[i-1]+a[i-2];
}
float b[20];//分母
b[0] = 1;b[1] = 2;
for(int i=2;i<=19;i++){
b[i] = b[i-1]+b[i-2];
}
float sum = 0;
for(int i=0;i<=19;i++){
sum = sum +a[i]/b[i];
}
printf("%f",sum);
return 0;
}
84.变量存储方式.cpp
#include<stdio.h>
int main(){
int fun(int x);
printf("%d\n",fun(1));//12
printf("%d\n",fun(1));
printf("%d\n",fun(1));
return 0;
}
int fun(int x){
static int a = 10;
a=a+1;
return (a+x);
}
85.指针.cpp
#include<stdio.h>
int main(){
int a =100;
printf("a=%d\n",a);
printf("a的地址：%d\n",&a);
return 0;
}
86.指针2.cpp
#include<stdio.h>
int main(){
int a =100;
// int *p1;//定义了一个指针变量
// p1 = &a;
int* p1 = &a;
*p1 = 88;
printf("a = %d\n",a);
printf("a = %d\n",&a);
printf("a = %d\n",p1);
printf("a = %d\n",*p1);
return 0;
}
87.指针3.cpp
#include<stdio.h>
int main(){
int a =10,b=20;
int *p1;int *p2;
p1 = &a;p2 = &b;
int c;
int *p=&c;
if(a<b){
*p =*p1;*p1 =*p2;
*p2=*p;
}
printf("max=%d,min=%d\n",*p1,*p2);
printf("max=%d,min=%d\n",a,b);
printf("%d\n",*p);
return 0;
}
88.指针4.cpp
#include<stdio.h>
int main(){
void swap(int*,int*);
int a = 10,b=20;
int *p1=&a;
int *p2 = &b;
if(a<b) swap(p1,p2);
printf("max=%d,min=%d\n",a,b);
return 0;
}
//如果指针变量作为形参，实参向形参传递地址
void swap(int *p1,int *p2){
int *p;
p = p1;
p1 = p2;
p2 = p;
}
89.指针5.cpp
#include<stdio.h>
int main(){
int a[10] ={3,1,2,8,6,1,6,10,7,8};
//a a[0]//a+1 a[1]
int *p;
p = a;
printf("%d\n",a);
printf("%d\n",p);
printf("%d\n",a+1);
printf("%d\n",p+1);
printf("%d\n",a[1]);
printf("%d\n",*(p+1));
printf("%d\n",a[3]);
printf("%d\n",*(p+3));
printf("%d\n",*(a+3));
return 0;
}
90.指针6.cpp
#include<stdio.h>
int main(){
int a[10] ={3,1,2,8,6,1,6,10,7,8};
for(int i=0;i<=9;i++){
printf("%d\t",a[i]);
}
printf("\n");
for(int i=0;i<=9;i++){
printf("%d\t",*(a+i));
}
printf("\n");
int *p = a;
for(int i=0;i<=9;i++){
printf("%d\t",*(p+i));
}
return 0;
}
91.指针7.cpp
#include<stdio.h>
int main(){
int a[5];
int *p;
p = a;
for(int i=0;i<=4;i++){
scanf("%d",p);
p = p+1;//p++
}
p = a;
for(int i=0;i<=4;i++){
printf("%d\t",*(p+i));
}
return 0;
}
92.真题1.cpp
#include<stdio.h>
int main(){
void inv(int a[],int n);
int a[10] = {1,2,3,4,5,6,7,8,9,0};
int *p = a;//int *p = &a[0];
for(int i=0;i<=9;i++){
printf("%d\t",*(p+i));
}
printf("\n");
inv(a,10);
for(int i=0;i<=9;i++){
printf("%d\t",*(p+i));
}
return 0;
}
void inv(int a[],int n){
int i;//数组前半部分的下标
int j; //数组后半部分的下标
int temp;//临时空间
int m = n/2; //101/2=50交换次数
for(i=0;i<m;i++){
j=n-1-i;//9=10-1=n-1-0 8=n-1-1 7=n-1-2 6=n-1-3
temp = a[i];
a[i] = a[j];
a[j] = temp;
}
}
93.真题2.cpp
#include<stdio.h>
int main(){
void inv(int *a,int n);
int a[10] = {1,2,3,4,5,6,7,8,9,0};
int *p = a;
for(int i=0;i<=9;i++){
printf("%d\t",*(p+i));
}
printf("\n");
inv(a,10);
for(int i=0;i<=9;i++){
printf("%d\t",*(p+i));
}
return 0;
}
void inv(int *a,int n){
int *i,*j;
i = a;//指针i指向数组的第一个元素
j = a+n-1; //指针j指向数组的最后一个元素
int m = n/2;
for(;i<(a+m);i++,j--){
int temp = *i;
*i = *j;
*j = temp;
}
}
94.指针字符串.cpp
#include<stdio.h>
int main(){
char str1[] = "helloworld";
//str1表示元素h的地址 \0结尾
printf("%s\n",str1);
//指针字符串
char *str2 = "I love you!";
//str2表示字符串第一个元素I的地址，
//也就是说，指针str2指向元素I，字符串以\0结尾.
printf("%s\n",str2);
printf("%c\n",*str2);
printf("%c\n",*(str2+3));
char s[20] = "beijing";
char *p;
p = s+1;
printf("%c\n",p[0]);
printf("%c\n",*p);
printf("%c\n",*(s+1));
printf("%c\n",s[1]);
return 0;
}
95.指针字符串2.cpp
#include<stdio.h>
int main(){
char a[] = "student";//\0
char b[20];
char *p1,*p2;
p1 = a;
p2 = b;
for(;*p1!='\0';p1++,p2++){
*p2 = *p1;
}
*p2 = '\0';
printf("%s",b);
return 0;
}
96.真题.cpp
#include<stdio.h>
int main(){
void fun(char *a,int *b);
char *a = "asdfgFGHJK45678";
int num = 0;
fun(a,&num);
printf("%d",num);
return 0; }
void fun(char *a,int *b){
int i = 0; int n=0;
while(*(a+i)!='\0'){
if(*(a+i)>='a'&&*(a+i)<='z') n++;
i++;}
*b = n;
}
97.二维数组的指针.cpp
#include<stdio.h>
int main(){
int a[3][4] = {{1,2,3,4},{5,6,7,8},{4,3,2,1}};
printf("%d\n",a); //第0行元素的地址
printf("%d\n",a+1);//第1行元素的地址
printf("%d\n",&a[0][0]);//第0行第0列元素的地址
printf("%d\n",*(a+0)+0);//第0行第0列元素的地址
printf("%d\n",*(*(a+0)+0));//第0行第0列元素的值
printf("%d\n",*(*(a+2)+2));//第2行第2列元素的值
printf("%d\n",*(a+1)+2);//第1行第2列元素的地址
printf("%d\n",*(*(a+1)+2));//第1行第2列元素的值
printf("%d\n",*a+1);//第0行第1列元素的地址
printf("%d\n",*(*a+1));//第0行第1列元素的值
printf("%d\n",a[1]+1);//第1行第1列元素的地址
printf("%d\n",*(a[1]+1));//第1行第1列元素的值
printf("%d\n",a[1][1]);//第1行第1列元素的值
printf("%d\n",a[0]);//第0行第0列元素的地址
printf("%d\n",*(a[0]));//第0行第0列元素的值
return 0;
}
98.二维数组的指针2.cpp
#include<stdio.h>
int main(){//RGB
int a[3][4] = {{1,2,3,4},{5,6,7,8},{4,3,2,1}};
int *p;//指向一个元素
p = &a[0][0];// p = a[0];p = *a
for(;p<a[0]+12;p++){//p = p+1
if((p-a[0])%4==0) printf("\n");
printf("%d\t",*p);
}
return 0;
}
99.二维数组的指针3.cpp
#include<stdio.h>
int main(){//RGB
int a[3][4] = {{1,2,3,4},{5,6,7,8},{4,3,2,1}};
int (*p)[4];//表示指向行的指针，这一行有4个元素。
p = a;
int i,j;
for(i=0;i<=2;i++){
for(j=0;j<=3;j++){
printf("%4d",*(*(p+i)+j));
}
printf("\n");
}
return 0;
}
100.函数指针.cpp
#include<stdio.h>
int main(){//RGB
int max(int,int);
int add(int,int);
int (*p)(int,int);//可以指向一个函数的指针。
//返回值为int类型，并且有 2个参数，并且每个参数的
//类型为int的函数
p = max; //函数的名称表示，函数的地址
int z = (*p)(7,8);
printf("%d\n",z);
p = add;
z = (*p)(7,8);
printf("%d\n",z);
return 0;
}
int max(int x,int y){
// if(x>y)return x;
// else return y;
int z = (x>y)? x:y;
return z;
}
int add(int x,int y){
return (x+y);
}
101.指针函数.cpp
#include<stdio.h>
#include<stdlib.h>
int main(){
int *p1;
//p1 = (int *)malloc(20); //分配5个int类型大小的空间
p1 = (int *)malloc(sizeof(int)*5);
for(int i=0;i<=4;i++){
scanf("%d",p1+i);
}
for(int i=0;i<=4;i++){
printf("%d\n",*(p1+i));
}
return 0;
}
102.结构体.cpp
#include<stdio.h>
#include<string.h>
struct Student {
int num;//学号
char name[20];//姓名
char sex;//性别
char addr[30];//地址
};
int main(){
//int i;
struct Student stu_1;
stu_1.num = 200101;
//strcpy()
strcpy(stu_1.name,"zhangsan");
stu_1.sex = 'F';
strcpy(stu_1.addr,"taiyuan");
printf("%d %s %c %s\n",
stu_1.num,stu_1.name,stu_1.sex,stu_1.addr);
struct Student stu_2;
stu_2.num = 200102;
//strcpy()
strcpy(stu_2.name,"lisi");
stu_2.sex = 'M';
strcpy(stu_2.addr,"beijing");
printf("%d %s %c %s",
stu_2.num,stu_2.name,stu_2.sex,stu_2.addr);
return 0;
}
103.结构体2.cpp
#include<stdio.h>
int main(){
struct Student {
int num;//学号
char name[20];//姓名
char sex;//性别
char addr[30];//地址
}stu_1={201001,"zhangsan",'F',"beijing"};
printf("%d %s %c %s\n",
stu_1.num,stu_1.name,stu_1.sex,stu_1.addr);
return 0;
}
103.结构体3.cpp
#include<stdio.h>
int main(){
struct{
int num;//学号
char name[20];//姓名
char sex;//性别
char addr[30];//地址
}stu_1={201001,"zhangsan",'F',"beijing"};
printf("%d %s %c %s\n",
stu_1.num,stu_1.name,stu_1.sex,stu_1.addr);
return 0;
}
104.结构体数组.cpp
#include<stdio.h>
struct Student{
int num;//学号
char name[20];//姓名
char sex;//性别
char addr[30];//地址
};
int main(){
struct Student stu[5]={
{200201,"zhangsan",'F',"taiyuan"},
{200202,"lisi",'F',"taiyuan"},
{200203,"wangwu",'M',"taiyuan"},
{200204,"zhaoliu",'F',"taiyuan"},
{200205,"sunqi",'M',"taiyuan"}};
for(int i=0;i<=4;i++){
printf("%d %s %c %s\n",
stu[i].num,stu[i].name,stu[i].sex,stu[i].addr);
}
return 0;
}
105.结构体指针.cpp
#include<stdio.h>
#include<string.h>
struct Student{
int num;//学号
char name[20];//姓名
char sex;//性别
char addr[30];//地址
};
int main(){
struct Student stu_1;
struct Student *p;
p = &stu_1;
stu_1.num = 200101;
strcpy(stu_1.name,"zhangsan");
stu_1.sex = 'F';
strcpy(stu_1.addr,"taiyuan");
printf("%d %s %c %s\n",
stu_1.num,stu_1.name,stu_1.sex,stu_1.addr);
printf("%d %s %c %s\n",
(*p).num,(*p).name,(*p).sex,(*p).addr);
printf("%d %s %c %s\n",
p->num,p->name,p->sex,p->addr);
return 0;
}
106.typedef.cpp
#include<stdio.h>
typedef int mao;
typedef float gou;
typedef double aaa;
int main(){
mao a = 100;
printf("%d\n",a);
int b = 101;
printf("%d\n",b);
return 0;
}
107.typedef2.cpp
#include<stdio.h>
#include<string.h>
typedef struct {
int num;//学号
char name[20];//姓名
char sex;//性别
char addr[30];//地址
}abc;
int main(){
abc stu_1;
stu_1.num = 200101;
strcpy(stu_1.name,"zhangsan");
stu_1.sex = 'F';
strcpy(stu_1.addr,"taiyuan");
printf("%d %s %c %s\n",
stu_1.num,stu_1.name,stu_1.sex,stu_1.addr);
return 0;
}
未命名6.cpp
#include<stdio.h>
#include<string.h>
int main(){
// char s[20]="dasdsad";
// char s1[20]={"dasdsad"};
// char *s2;
// s2 = {"sdasadsa"};
// char *s3;
// s3 = "sdasadsa";
// char *s4= "sdasadsa";
// char *s5= {"sdasadsa"};
char *s = "abcde";
s+=2;//s =s+2;
printf("%d\n",s);
char str[] ="hello!";
printf("%d\n",strlen(str));
printf("%d\n",sizeof(str));
return 0;
}
