C语言经典代码练习题

1.输入一个4位数：输出这个输的个位十位百位千位

#include <stdio.h>
int main(int argc, char const *argv[])
{int a;printf("输入一个４位数：");scanf("%d",&a);printf("个位：%d\n",a%10);printf("十位：%d\n",a%100/10);printf("百位：%d\n",a/100%10);printf("千位：%d\n",a/1000);return 0;
}

2.从键盘读入两个整数，输出他们的和

#include <stdio.h>
int main(int argc, char const *argv[])
{int a,b;printf("输入第一个整数:");scanf("%d",&a);printf("输入第二个整数:");scanf("%d",&b);printf("它们的和:%d\n",a+b);return 0;
}

3.一个水分子的质量约为3.0*10^-23g，1夸脱水大约有950g，编写一个程序，要求输入水的夸脱数，然后显示这么多水中包含多少水分子。表示：3.0e-23 打印格式：%f或%e

#include <stdio.h>
int main(int argc, char const *argv[])
{int a;printf("输入水的夸脱数：");scanf("%d",&a);printf("%d夸脱水包含%f水分子\n",a,a*950/3.0e-23);return 0;
}

4.实现大小写转换（用getchar、putchar实现）即如果是大写字母转成小写输出如果是小写字母转为大写输出。

#include <stdio.h>
int main(int argc, char const *argv[])
{int a=getchar();if(65<=a&&a<=90){putchar(a+32);putchar(10);}else if (a>=97&&a<=122){putchar(a-32);putchar(10);}return 0;
}

5.从终端输入3个整数;从大到小输出。

#include <stdio.h>
int main(int argc, char const *argv[])
{int a, b, c;printf("请输入三个整数：\n");scanf("%d%d%d", &a, &b, &c);if (a <= b){int m;m = a;a = b;b = m;}if (b >= c)printf("%d %d %d\n", a, b, c);else if (a >= c && c >= b)printf("%d %d %d\n", a, c, b);elseprintf("%d %d %d\n", c, a, b);return 0;
}

6.输入任意两个数，输出两数之间(包括这两个数)偶数之和

#include <stdio.h>
int main(int argc, char const *argv[])
{int a, b, c;int sum = 0;printf("输入任意两个数:\n");scanf("%d%d", &a, &b);if (a > b){c = a;a = b;b = c;}for (int i = a; i <= b; i++){if (i % 2 == 0)sum += i;}printf("%d与%d偶数之和为%d\n", a, b, sum);return 0;
}

7.写程序实现功能：读入两个整数(data1和data2)和一个运算符(op),计算表达式data1 op data2 的值.其中op可以为+、-、*、/四个符号中的任一种（用switch语句实现）

#include <stdio.h>
int main(int argc, char const *argv[])
{int a, b;char c;printf("输入两个整数:\n");scanf("%d%d", &a, &b);getchar();printf("输入一个运算符(+、－、＊、／):\n");scanf("%c", &c);switch (c){case '+':printf("%d%c%d=%d\n", a, c, b, a + b);break;case '-':printf("%d%c%d=%d\n", a, c, b, a - b);break;case '*':printf("%d%c%d=%d\n", a, c, b, a * b);break;case '/':printf("%d%c%d=%d\n", a, c, b, a / b);break;}return 0;
}

8.终端输入十个数，去掉其中最大值和最小值，求平均值。

#include <stdio.h>
int main(int argc, char const *argv[])
{int a[10];int max, min;int sum = 0;printf("输入十个数:\n");for (int i = 0; i < 10; i++){scanf("%d", &a[i]);sum += a[i];}for (int i = 0; i < 10; i++){max = a[0];min = a[0];if (a[i] > max)max = a[i];if (a[i] < min)min = a[i];}printf("sum=%d\n", sum);printf("max=%d\n", max);printf("min=%d\n", min);printf("去掉最大值和最小值，平均值为:%f\n", (float)(sum - max - min) / 8);return 0;
}

9.计算斐波那契数列前15项并逆序输出。

#include <stdio.h>
int main(int argc, char const *argv[])
{int a[15] = {1, 1};for (int i = 2; i < 15; i++){a[i] = a[i - 2] + a[i - 1];}for (int i = 14; i >= 0; i--)printf("%d\n", a[i]);return 0;
}

10.循环输入一个5位数，判断它是不是回文数。当输入0时循环结束。即12321是回文数，个位与万位相同，十位与千位相同。

#include <stdio.h>
int main(int argc, char const *argv[])
{int a;printf("输入一个５位数:");while (1){scanf("%d", &a);if (a == 0)break;if ((a % 10 == a / 10000) && (a / 10 % 10 == a / 1000 % 10))printf("是回文数\n");elseprintf("不是回文数\n");printf("输入一个５位数:");}return 0;
}

11.输入一个字符串，大小写转换输出。

#include <stdio.h>
#include <string.h>
int main(int argc, char const *argv[])
{char a[33] = {};scanf("%s", a);int n = strlen(a);for (int i = 0; i < n; i++){if (a[i] >= 'a' && a[i] <= 'z')printf("%c", a[i] - 32);else if (a[i] >= 'A' && a[i] <= 'Z')printf("%c", a[i] + 32);}return 0;
}

12.冒泡排序。

#include <stdio.h>
int main(int argc, char const *argv[])
{int a[5] = {6, 5, 4, 2, 3};for (int i = 0; i < 4; i++){for (int j = 0; j < 4 - i; j++){if (a[j] > a[j + 1]){a[j] = a[j] ^ a[j + 1];a[j + 1] = a[j] ^ a[j + 1];a[j] = a[j] ^ a[j + 1];}}}for (int i = 0; i < 5; i++){printf("%d", a[i]);}return 0;
}

13.选择排序。

#include <stdio.h>
int main(int argc, char const *argv[])
{int a[5] = {5, 4, 6, 9, 7};int temp;for (int i = 0; i < 4; i++){int min = i;for (int j = i + 1; j < 5; j++){if (a[j] < a[min])min = j;}temp=a[i];a[i]=a[min];a[min]=temp;}for (int i = 0; i < 5; i++)printf("%d", a[i]);return 0;
}

14.字符串逆序输出(两种方法实现)。

#include <stdio.h>
#include <string.h>
int main(int argc, char const *argv[])
{// 字符串逆序输出// 法１// char a[] = "hello world";// char *p = a;// int n = strlen(a);// for (int i = n; i >= 0; i--)// {//     printf("%c ", p[i]);// }char a[] = "hello world";char *p = a + strlen(a) - 1;for (int i = 0; i < strlen(a); i++){printf("%c", *p);p--;}// 法２// char a[] = "hello world";// char *p = a;// int n = strlen(a);// for (int i = 0; i < n / 2; i++)// {//     p[i] = p[i] ^ p[n - i - 1];//     p[n - i - 1] = p[i] ^ p[n - i - 1];//     p[i] = p[i] ^ p[n - i - 1];// }// printf("%s", p);// return 0;char a[66];gets(a);char *p = a;char *q = a + strlen(a) - 1;while (p < q){*p = *p ^ *q;*q = *p ^ *q;*p = *p ^ *q;p++;q--;}printf("%s", a);return 0;
}

15.字符串转数字："1234" -----> 1234(一千两百三十四)。

#include <stdio.h>
#include <string.h>
int main(int argc, char const *argv[])
{// 字符串转数字//法１// char a[33];// gets(a);// int n=strlen(a);// int sum=0;// int j;// for (int i = 1; i < n; i++)// {//     j*=10;// }   // for (int i = 0; i < n; i++)// {//     sum+=(a[i]-48)*j;//     j/=10;// }// printf("%d\n", sum);// return 0;//法２char a[33];gets(a);char *p=a;int n=0;while (*p!='\0'){n=n*10+(*p-48);p++;}printf("%d\n",n);
}

16.打印杨辉三角前十行(二维数组)。

#include <stdio.h>
int main(int argc, char const *argv[])
{// 打印杨辉三角前十行// 法１//  int a[10][10] = {0};//  for (int i = 0; i < 10; i++)//  {//      for (int j = 0; j <= i; j++)//      {//          if (j - 1 >= 0)//              a[i][j] = a[i - 1][j - 1] + a[i - 1][j];//          else//              a[i][j] = 1;//      }//  }//  for (int i = 0; i < 10; i++)//  {//      for (int j = 0; j <= i; j++)//          printf("%-3d ", a[i][j]);//      printf("\n");//  }// 法２int a[10][10] = {};for (int i = 0; i < 10; i++){a[i][0] = 1;a[i][i] = 1;}for (int i = 2; i < 10; i++){for (int j = 1; j < 10; j++)a[i][j] = a[i - 1][j - 1] + a[i - 1][j];}for (int i = 0; i < 10; i++){for (int j = 0; j <= i; j++)printf("%d ", a[i][j]);putchar(10);}
}

17.已知字符数组a[10]和b[10]中元素的值递增有序，用指针实现将两个数组中元素按照递增顺序输出。如：char a[10]=”acdgjmno” ; char b[10]=”befhil”;->”abcdefghijlmno”

#include <stdio.h>
#include <string.h>
int main(int argc, char const *argv[])
{char a[10] = "acdgjmno";char b[10] = "befhil";char *p = a, *q = b;int i = 0, j = 0;while (i < strlen(a) && j < strlen(b)){if (p[i] < q[j]){printf("%c", p[i]);i++;}else{printf("%c", q[j]);j++;}}if (i < strlen(a)){for (int k = i; k < strlen(a); k++)printf("%c", a[k]);}if (j < strlen(b)){for (int k = j; k < strlen(b); k++)printf("%c", b[k]);}return 0;
}

18.给定一串字符"I love china",实现以单词为单位的逆序，如："china love i"

#include <stdio.h>
#include <string.h>
int main(int argc, char const *argv[])
{char a[] = "i love china";char *p = a;int n = strlen(a);for (int i = 0; i < n / 2; i++){p[i] = p[i] ^ p[n - i - 1];p[n - i - 1] = p[i] ^ p[n - i - 1];p[i] = p[i] ^ p[n - i - 1];}char *q;char *k=NULL, temp;p = q = a;while (*p != '\0'){while (*p == ' ' )p++;q = p;while (*q != ' ' && *q != '\0')q++;k = q;q = k - 1;while (p < q){temp = *p;*p = *q;*q = temp;p++;q--;}p = k;}printf("%s\n", a);return 0;
}

19.定义求x的n次方值的函数（ x是实数, n为正整数）。

#include <stdio.h>int fun(int x, int n)
{int r = 1;for (int i = 0; i < n; i++)r *= x;printf("%d\n", r);return r;
}int main(int argc, char const *argv[])
{// int r = 1;// int x = 2;// for (int i = 0; i < 4; i++)//     r *= x;// printf("%d\n", r);printf("%d\n", fun(2, 4));
}

20.编写一个函数，函数的2个参数，第一个是一个字符，第二个是一个char *,返回字符串中该字符的个数。

#include <stdio.h>int fun(char ch, char *p)   //ch=a='a', p=s
{int n = 0;while (*p != '\0') //*p{if (*p == ch)n++;p++; //p=p+1}return n;
}int main(int argc, char const *argv[])
{char a = 'a';char s[32] = "abbba";printf("%d\n", fun(a, s));
}

21.编程实现strlen函数的功能，strlen计算字符串实际长度，不包含'\0'

#include <stdio.h>int fun(char *p)
{int n = 0;while (*p){n++;p++;}return n;
}int main(int argc, char const *argv[])
{char s[32] = "abbba";int len = 0;len = fun(s);printf("%d\n", len);//printf("%d\n", fun(s));//printf("%d\n", fun("6666666"));
}

22.字符串"123"转换成整型123

#include <stdio.h>int fun(char *p)
{int sum = 0;while (*p != '\0'){sum = sum * 10 + (*p - 48);p++;}return sum;
}int main(int argc, char const *argv[])
{char str[32] = "123";printf("%d\n", fun(str));
}

23.封装函数实现两数交换。

#include <stdio.h>
void fun(int *x, int *y)
{int tmp;tmp = *x;*x = *y;*y = tmp;
}int main(int argc, char const *argv[])
{int a = 10, b = 20;fun(&a, &b);printf("%d %d\n", a, b);
}

24.封装函数实现strcpy功能。

#include <stdio.h>void fun(char *p, char *q)
{while (*q != '\0')*p++ = *q++;  //*p=*q; p++; q++;*p = '\0';
}int main(int argc, char const *argv[])
{char a[32] = "";char b[32] = "hello";fun(a, b);printf("%s\n", a);
}

25.封装函数实现strcat功能。

#include <stdio.h>
#include <string.h>
void fun(char *p, char *q)
{while (*p)   //p=p+strlen(p);p++;while (*q)*p++ = *q++;*p = '\0';
}int main(int argc, char const *argv[])
{char a[32] = "hello";char b[32] = "world";fun(a, b);printf("%s\n", a);
}

26.用递归函数求5的阶乘5！

#include <stdio.h>
#include <string.h>int fac(int n)   //n=5  n=4 n=3 n=2 n=1
{if (n == 1)return 1;       //fac(1)=1if (n > 1)return n * fac(n - 1);  //递推阶段：5*fac(4)  fac(4)=4*fac(3) fac(3)=3*fac(2) fac(2)=2*fac(1)//回归阶段：==> fac2(2)=2*1=2 ==>fac(3)=3*2=6 ==> fac(4)=4*6=24 ==>fac(5)=5*24=120
}int main(int argc, char const *argv[])
{int n = 5;printf("%d\n", fac(n));
}

27.斐波那契数列：指的是这样一个数列：1、1、2、3、5、8、13、21、34、……在数学上，斐波纳契数列以如下被以递归的方法定义：F(1)=1，F(2)=1, F(n)=F(n-1)+F(n-2)（n>=2，n∈N*）求第五个数。

#include <stdio.h>
#include <string.h>int fac(int n)   //5 4 
{if (n == 1 || n == 2)return 1;if (n > 2)return fac(n - 1) + fac(n - 2);   //fac(5)=fac(4)+fac(3)= fac(3)+fac(2) +fac(3) = 5
}int main(int argc, char const *argv[])
{int n = 5;printf("%d\n", fac(n));
}

28.创建一个名为student的结构体，包含姓名，学号，班级,从终端输入学生的信息并打印。

#include <stdio.h>
#include <string.h>
struct student
{char name[32];int id;int class;
};struct student s1;
int main(int argc, char const *argv[])
{scanf("%s %d %d", s1.name, &s1.id, &s1.class);printf("%s %d %d\n", s1.name, s1.id, s1.class);
}

29.typedef用法

#include <stdio.h>
#include <string.h>
//1.给普通变量重命名
typedef int size4;//2. 给指针类型重命名
typedef int *int_p;//3. 给数组类型重名
typedef int intArr5[5];int main()
{size4 a = 10;                    //等同于int a=10;int_p p = &a;                    //等同于int *p=&a;intArr5 arr = {1, 2, 3, 4, 5}; //等同于int arr[5]={1,2,3,4,5};printf("%d\n", *p);     //10printf("%d\n", arr[3]);  //4
}

30.创建一个描述手机的结构体叫phone, 包含品牌，型号，颜色，价格。从终端输入你自己手机的信息并打印。(用typedef)。

#include <stdio.h>
#include <string.h>
typedef struct phone
{char brand[32];char type[32];char color[32];int price;
} ph;ph my;
int main()
{scanf("%s %s %s %d", my.brand, my.color, my.type, &my.price);printf("%s %s %s %d\n", my.brand, my.color, my.type, my.price);
}

31.创建一个名为student的结构体数组，包含学号，姓名，成绩,(数据类型自己定义),从终端输入学生的信息并打印分数及格的学生信息（输入3人即可）。

#include <stdio.h>
typedef struct student
{char name[32];int number;int score;
} st;int main(int argc, char const *argv[])
{st s[3];for (int i = 0; i < 3; i++)scanf("%s %d %d", s[i].name, &s[i].number, &s[i].score);for (int i = 0; i < 3; i++){if (s[i].score >= 60)printf("%s %d %d\n", s[i].name, s[i].number, s[i].score);}return 0;
}

32.创建一个结构体数组，数组名为book，结构体成员包含编号，书名，售价（数据类型自己设定）。写一个函数，包含两个形参，分别接收结构体数组的首地址和一个指定的售价，函数的功能为打印结构体数组中售价大于指定售价的书的信息。

#include <stdio.h>
#define N 3
typedef struct book
{char name[32];int id;int price;
} BOOK; //BOOK等同于struct bookBOOK b[N] = {{"shuihu", 1, 40},{"zyj zhuan", 2, 200},{"tuling zhuan", 3, 0}};void bookPri(BOOK *p, int n)
{for (int i = 0; i < N; i++){if (p->price > n)printf("%s %d %d\n", p->name, p->id, p->price);p++;}
}int main(int argc, char const *argv[])
{bookPri(b, 6);return 0;
}

33.创建一个游戏英雄的结构体数组(5个元素), 结构体成员包含名称, 血量和价格。给出每个英雄信息，封装函数实现按价格从低到高打印英雄信息，（用冒泡排序）。封装函数实现修改英雄信息功能。

#include <stdio.h>typedef struct hero
{char name[32];int hp;int price;
} HERO;void sort(HERO *p, int n)
{HERO tmp;for (int i = 0; i < n - 1; i++){for (int j = 0; j < n - i - 1; j++){if (p[j].price > p[j + 1].price){tmp = p[j];p[j] = p[j + 1];p[j + 1] = tmp;}}}
}void change(HERO *p, int n)
{if (n <= 3)scanf("%s %d %d", p[n - 1].name, &p[n - 1].hp, &p[n - 1].price);elseprintf("err\n");
}int main(int argc, char const *argv[])
{HERO a[3] = {{"zdl", 1, 50},{"zyj", 999, 100},{"xyb", 10000, 2}};change(a, 1);sort(a, 3);for (int i = 0; i < 3; i++)printf("%s %d %d\n", a[i].name, a[i].hp, a[i].price);return 0;
}

34.封装函数实现冒泡排序。

#include <stdio.h>void fun(int *a, int n)
{for (int i = 0; i < n - 1; i++){for (int j = 0; j < n - 1 - i; j++){if (a[j + 1] > a[j]){int temp = a[j];a[j] = a[j + 1];a[j + 1] = temp;}}}for (int i = 0; i < 10; i++)printf("%d ", a[i]);printf("\n");
}int main(int argc, char const *argv[])
{int a[10] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};fun(a, 10);return 0;
}

35.封装函数实现如下功能：输入任意两个数，返回两数之间（包括这两个数）偶数之和。

#include <stdio.h>int fun(int a, int b)
{int sum = 0;if (a >= b){int t = a;a = b;b = t;}for (int i = a; i <= b; i++){if (i % 2 == 0)sum += i;}return sum;
}int main(int argc, char const *argv[])
{int a, b, sum;scanf("%d %d", &a, &b);sum = fun(a, b);printf("%d\n", sum);return 0;
}