【解】
#include <iostream>
#include <iomanip>
using namespace std;
#include <cmath>
int main()
{
int i, j, n, a[101]; //定义a数组包含101个元素
for (i = 1; i <= 100; i++) //a[0]不用, 只用a[1]~a[100]
a[i] = i; //使a[1]~a[100]的值为1~100
a[1] = 0; //先“挖掉”a[1]
for (i = 2; i < sqrt(100); i++)
for (j = i + 1; j <= 100; j++)
{
if (a[i] != 0 && a[j] != 0)
if (a[j] % a[i] == 0)
a[j] = 0;
} //把非素数“挖掉”
cout << endl;
for (i = 1, n = 0; i <= 100; i++)
{
if (a[i] != 0) //选出值不为0的数组元素, 即素数
{
cout << setw(5) << a[i] << " "; //输出素数, 宽度为5列
n++;
} //累计本行已输出的数据个数
if (n == 10) //输出10个数后换行
{
cout << endl;
n = 0;
}
}
cout << endl;
return 0;
}运行结果：
//2 ? ?3 ? ?5 ? ?7 ? 11 ? 13 ? 17 ? 19 ? 23 ? 29
//31 ? 37 ? 41 ? 43 ? 47 ? 53 ? 59 ? 61 ? 67 ? 71
//73 ? 79 ? 83 ? 89 ? 97
【解】
#include <iostream>
using namespace std;
int main()
{
int i, j, min, temp, a[11];
cout << "enter data:" << endl;
for (i = 1; i <= 10; i++)
{
cout << "a[" << i << "]=";
cin >> a[i]; //输入10个数
}
cout << endl << "The original numbers:" << endl;
for (i = 1; i <= 10; i++)
cout << a[i] << " "; //输出这10个数
cout << endl;
for (i = 1; i <= 9; i++) //以下8行是对10个数排序
{
min = i;
for (j = i + 1; j <= 10; j++)
if (a[min] > a[j]) min = j;
temp = a[i]; //以下3行将a[i+1]~a[10]中最小者与a[i]对换
a[i] = a[min];
a[min] = temp;
}
cout << endl << "The sorted numbers:" << endl;
for (i = 1; i <= 10; i++) //输出已排好序的10个数
cout << a[i] << " ";
cout << endl;
return 0;
}运行结果：
//enter data :
//a[1] = 36 ↙
//a[2] = – 9↙
//a[3] = 5↙
//a[4] = 6↙
//a[5] = –1↙
//a[6] = 35↙
//a[7] = 34↙
//a[8] = 738↙
//a[9] = 18↙
//a[10] = 11↙
//The original numbers :
//36 –9 5 6 –1 35 34 738 18 11
//The sorted numbers :
//–9 –1 5 6 11 18 34 35 36 738
【解】
#include <iostream>
using namespace std;
int main()
{
int a[3][3], sum = 0;
int i, j;
cout << "enter data:" << endl;
for (i = 0; i < 3; i++)
for (j = 0; j < 3; j++)
cin >> a[i][j];
for (i = 0; i < 3; i++)
sum = sum + a[i][i];
cout << "sum=" << sum << endl;
return 0;
}
运行结果：
//enter ata：
//1 3 5 7 9 11 13 15 17↙
//sum = 27
【解】
#include <iostream>
using namespace std;
int main()
{
int a[11] = { 1, 6, 13, 17, 28, 40, 56, 78, 89, 100 };
int num, i, j;
cout << "array a:" << endl;
for (i = 0; i < 10; i++)
cout << a[i] << " ";
cout << endl;
cout << "insert data:";
cin >> num;
if (num > a[9])
a[10] = num;
else
{
for (i = 0; i < 10; i++)
{
if (a[i] > num)
{
for (j = 9; j >= i; j--)
a[j + 1] = a[j];
a[i] = num;
break;
}
}
}
cout << "Now, array a:" << endl;
for (i = 0; i < 11; i++)
cout << a[i] << " ";
cout << endl;
return 0;
}运行结果：
//array a:
//1 6 13 17 28 40 56 78 89 100
//insert data : 15↙
//Now, array a :
//1 6 13 15 17 28 40 56 78 89 100
【解】
#include <iostream>
using namespace std;
int main()
{
const int n = 5;
int a[n], i, temp;
cout << "enter array a:" << endl;
for (i = 0; i < n; i++)
cin >> a[i];
cout << "array a:" << endl;
for (i = 0; i < n; i++)
cout << a[i] << " ";
for (i = 0; i < n / 2; i++) //循环的作用是将对称的元素的值互换
{
temp = a[i];
a[i] = a[n-i-1];
a[n-i-1] = temp;
}
cout << endl << "Now,array a:" << endl;
for (i = 0; i < n; i++)
cout << a[i] << " ";
cout << endl;
return 0;
}运行结果：
//enter array a:
//9 8 7 6 5↙
//array a :
//9 8 7 6 5
//Now, array a :
//5 6 7 8 9
【解】
#include <iostream>
#include <iomanip>
using namespace std;
int main()
{
const int n = 11;
int i, j, a[n][n]; //数组为11行11列, 0行0列不用
for (i = 1; i < n; i++)
{
a[i][1] = 1; //使第1列元素的值为1
a[i][i] = 1; //使对角线元素的值为1
}
for (i = 3; i < n; i++) //从第3行开始处理
for (j = 2; j <= i - 1; j++)
a[i][j] = a[i - 1][j - 1] + a[i - 1][j];
for (i = 1; i < n; i++) //输出数组各元素的值
{
for (j = 1; j <= i; j++)
cout << setw(6) << a[i][j] << " ";
cout << endl;
}
cout << endl;
return 0;
}运行结果：
//1
//1 ? ? 1
//1 ? ? 2 ? ? 1
//1 ? ? 3 ? ? 3 ? ? 1
//1 ? ? 4 ? ? 6 ? ? 4 ? ? 1
//1 ? ? 5 ? ?10 ? ?10 ? ? 5 ? ? 1
//1 ? ? 6 ? ?15 ? ?20 ? ?15 ? ? 6 ? ? 1
//1 ? ? 7 ? ?21 ? ?35 ? ?35 ? ?21 ? ? 7 ? ? 1
//1 ? ? 8 ? ?28 ? ?56 ? ?70 ? ?56 ? ?28 ? ? 8 ? ? 1
//1 ? ? 9 ? ?36 ? ?84 ? 126 ? 126 ? ?84 ? ?36 ? ? 9 ? ? 1
【解】
#include <iostream>
using namespace std;
int main()
{
const int n = 4, m = 5; //假设数组为4行5列
int i, j, a[n][m], max, maxj;
bool flag;
for (i = 0; i < n; i++) //输入数组
for (j = 0; j < m; j++)
cin >> a[i][j];
for (i = 0; i < n; i++)
{
max = a[i][0]; maxj = 0; //开始时假设a[i][0]最大, 将列号(0)赋给maxj保存
for (j = 0; j < m; j++) //找出第i行中的最大数
if (a[i][j] > max)
{
max = a[i][j]; //将本行的最大数存放在max中
maxj = j; //将最大数所在的列号存放在maxj中
}
flag = true; //先假设是鞍点, 用flag为真来代表
for (int k = 0; k < n; k++)
if (max > a[k][maxj]) //将最大数和其同列元素相比
{
flag = false; //如果max不是同列最小, 表示不是鞍点, 令flag为假
continue;
}
if (flag) //如果flag为真, 表示是鞍点
{
cout << "a[" << i << "][" << "[" << maxj << "]=" << max << endl;
//输出鞍点的值和所在行列号
break;
}
}
if (!flag) //如果flag为假表示鞍点不存在
cout << "It does not exist!" << endl;
return 0;
}运行结果：
//① 1 2 3 4 5↙?? ??? ??? ??? ??? ?（输入4行5列数据）
//2 4 6 8 10↙
//3 6 9 12 15↙
//4 8 12 16 20↙
//a[0][4] = 5?? ??? ??? ??? ??? ?（0行4列元素是鞍点, 其值为5）
//② 1 12 3 4 5↙?? ??? ??? ??? ??? ?（输入4行5列数据)
//2 4 16 8 10↙
//3 6 9 12 15↙
//4 8 12 16 20↙
//It does not exist!（无鞍点）
【解】
#include <iostream>
using namespace std;
int main()
{
const int n = 7;
int i, number, top, bott, mid, loca, a[n];
bool flag = true, sign;
char c;
cout << "enter data:" << endl;
cin >> a[0];
i = 1;
while (i < n)
{
cin >> a[i];
if (a[i] >= a[i - 1])
i++;
else
cout << "enter this data again:";
}
cout << endl;
for (i = 0; i < n; i++)
cout << a[i] << " ";
cout << endl;
while (flag)
{
cout << "input number to look for:";
cin >> number;
sign = false; //sign为假表示尚未找到
top = 0; //top是查找区间的起始位置
bott = n - 1; //bott是查找区间的最末位置
if ((number < a[0]) || (number > a[n - 1])) //要查的数不在查找区间内
loca = - 1; //表示要查找的数不在正常范围内
while ((!sign) && (top <= bott))
{
mid = (bott + top) / 2; //找出中间元素的下标
if (number == a[mid]) //如果要查找的数正好等于中间元素
{
loca = mid; //记下该下标
cout << "Find " << number << ", its position is " << loca + 1 << endl;
//由于下标从0算起, 而人们习惯从1算起, 因此输出数的位置时要加1
sign = true; //表示找到了
}
else if (number < a[mid]) //如果要查找的数小于中间元素的值
bott = mid - 1; //只须从下标为0~mid - 1的范围中找
else //如果要查找的数不小于中间元素的值
top = mid + 1; //只须从下标为mid+1~bott的范围中找
}
if (!sign || loca == - 1) //sign为假或loca等于 - 1, 意味着找不到
cout << number << " has not found." << endl;;
cout << "continue or not(Y/N)?";
cin >> c;
if (c == 'N' || c == 'n')
flag = false; //flag为开关变量, 控制程序是否结束运行
}
return 0;
}运行结果：
//enter data : （输入数据）
//6 8 12 10↙?? ?（数据未按由小到大顺序输入）
//enter this data again : （要求重新输入)
//23 34 44 45 56 57 58↙
//68 69 76 90 109↙
//6 8 12 23 34 44 45 56 57 58 68 69 76 90 109?? ?（输出这15个数）
//input number to look for:7↙?? ?（寻找7）
//7 has not found.（在数组中找不到7）
//Continue or not(Y / N) ? y↙?? ?（需要继续查找）
//input number to look for : 12↙?? ?（寻找12）
//12, its position is 3?? ?（12是第3个数）
//Continue or not(Y / N) ? n↙?? ?（不再继续查找）
//（运行结束）
【解】
#include <iostream>
using namespace std;
int main()
{
int sum_day(int, int);
int leap(int year);
int year, month, day, days;
cout << "input date(year,month,day):";
cin >> year >> month >> day;
cout << year << "/" << month << "/" << day;
days = sum_day(month, day); //调用sum_day函数计算日期
if (leap(year) && month >= 3) //若year是闰年, 且月份在3月以后
days = days + 1; //days多加1天
cout << " is the " << days << "th day in this year." << endl;
return 0;
}
int sum_day(int month, int day) //计算日期
{
int i;
int day_tab[12] = { 31,28,31,30,31,30,31,31,30,31,30,31 };
for (i = 0; i < month - 1; i++)
day += day_tab[i];
return(day);
}
int leap(int year) //判断year是否为闰年
{
int leap;
leap = year % 4 == 0 && year % 100 != 0 || year % 400 == 0;
return(leap);
}运行结果：
//input date(year, month, day) :2005 10 1↙
//2005 / 10 / 1 is the 274th day in this year.
【解】
#include <iostream>
using namespace std;
int main()
{
int i, j, upper, lower, digit, space, other;
char text[3][80];
upper = lower = digit = space = other = 0;
for (i = 0; i < 3; i++)
{
cout << "please input line " << i + 1 << endl;
gets_s(text[i]);
for (j = 0; j < 80 && text[i][j] != '\0'; j++)
{
if (text[i][j] >= 'A'&& text[i][j] <= 'Z')
upper++;
else if (text[i][j] >= 'a' && text[i][j] <= 'z')
lower++;
else if (text[i][j] >= '0' && text[i][j] <= '9')
digit++;
else if (text[i][j] == ' ')
space++;
else
other++;
}
}
cout << "upper case:" << upper << endl;
cout << "lower case:" << lower << endl;
cout << "digit :" << digit << endl;
cout << "space :" << space << endl;
cout << "other :" << other << endl;
return 0;
}运行结果：
//please input line 1:
//I am a boy.↙
//please input line 2：
//You are a girl; ↙
//please input line 3:
//12 + 34 = 46↙
//upper case: 2
//lower case: 16
//digit : 6
//space : 6
//other : 4
【解】
//（1）用字符数组方法，程序如下：
#include <iostream>
using namespace std;
int main()
{
char a[5] = { '*','*','*','*','*' };
int i, j, k;
const char space = ' ';
for (i = 0; i < 5; i++) //输出5行
{
cout << endl; //输出每行前先换行
cout << " "; //每行前面留4个空格
for (j = 1; j <= i; j++)
cout << space; //每行再留一个空格
for (k = 0; k < 5; k++)
cout << a[k]; //每行输出5个*号
}
cout << endl;
return 0;
}
//（2）用string方法，程序如下：
#include <iostream>
#include <string>
using namespace std;
int main()
{
string stars = "*****";
int i, j;
for (i = 0; i < 5; i++) //输出5行“*****”
{
cout << " "; //每行前面留4个空格
for (j = 1; j <= i; j++)
cout << " "; //每行再插入i个空格
cout << stars << endl; //输出“*****”
}
return 0;
}运行结果：
?? ?*****
?? ? *****
?? ? ?*****
?? ? ? *****
?? ? ? ?*****
【解】
//（1）用字符数组方法
#include <iostream>
using namespace std;
int main()
{
int j, n;
char ch[80], tran[80];
cout << "?input cipher code:";
gets_s(ch);
cout << "cipher code:" << ch << endl;
j = 0;
while (ch[j] != '\0')
{
if ((ch[j] >= 'A') && (ch[j] <= 'Z')) //判断是否为大写字母
tran[j] = 155 - ch[j]; //字母转换
else if ((ch[j] >= 'a') && (ch[j] <= 'z')) //判断是否为小写字母
tran[j] = 219 - ch[j]; //字母转换
else
tran[j] = ch[j]; //非字母不转换
j++;
}
n = j; //n为电文中字符个数
cout << "original text:";
for (j = 0; j < n; j++)
putchar(tran[j]);
cout << endl;
return 0;
}
//（2）也可以不必定义两个字符数组，而只用一个字符数组。程序如下：
#include <iostream>
using namespace std;
int main()
{
int j, n;
char ch[80];
cout << "input cipher code:";
gets_s(ch);
cout << "cipher code:" << ch << endl;
j = 0;
while (ch[j] != '\0')
{
if ((ch[j] >= 'A') && (ch[j] <= 'Z'))
ch[j] = 155 - ch[j];
else if ((ch[j] >= 'a') && (ch[j] <= 'z'))
ch[j] = 219 - ch[j];
else
ch[j] = ch[j];
j++;
}
n = j;
cout << "original text:";
for (j = 0; j < n; j++)
putchar(ch[j]);
cout << endl;
return 0;
}
//（3）用string方法
#include <iostream>
#include <string>
using namespace std;
int main()
{
int j;
string ch = "I will visit China next week.", tran;
tran = ch; //使tran也占同样大小的存储单元
cout << "cipher code:" << ch << endl;
j = 0;
while (j <= ch.size()) //用 ch.size( )测定ch的长度
{
if ((ch[j] >= 'A') && (ch[j] <= 'Z'))
tran[j] = 155 - ch[j];
else if ((ch[j] >= 'a') && (ch[j] <= 'z'))
tran[j] = 219 - ch[j];
else
tran[j] = ch[j];
j++;
}
cout << "original text:";
cout << tran << endl;
return 0;
}
//（4）也可以只用一个字符串变量ch
#include <iostream>
#include <string>
using namespace std;
int main()
{
int j;
string ch = "I will visit China next week.";
cout << "cipher code:" << ch << endl;
j = 0;
while (j <= ch.size())
{
if ((ch[j] >= 'A') && (ch[j] <= 'Z'))
ch[j] = 155 - ch[j];
else if ((ch[j] >= 'a') && (ch[j] <= 'z'))
ch[j] = 219 - ch[j];
j++;
}
cout << "original text:";
cout << ch << endl;
return 0;
}
//（5）使用字符串变量，由键盘输入电文。程序如下：
#include <iostream>
#include <string>
using namespace std;
int main()
{
int j;
string ch = " "; //ch的初始值为若干空格
char *p = &ch[0]; //定义字符指针并使之指向ch的首字符
cout << "input cipher code:";
gets(p); //从键盘读入一行字符
cout << "cipher code:" << ch << endl;
j = 0;
while (j <= ch.size())
{
if ((ch[j] >= 'A') && (ch[j] <= 'Z'))
ch[j] = 155 - ch[j];
else if ((ch[j] >= 'a') && (ch[j] <= 'z'))
ch[j] = 219 - ch[j];
j++;
}
cout << "original text:";
cout << ch << endl;
return 0;
}运行结果：
//input cipher code : R droo erhrg Xsrmz mvcg dvvp.↙?? ?（输入电文）
//cipher code : R droo erhrg Xsrmz mvcg dvvp.（显示电文）
//original text : I will visit China next week.（译成原文）
【解】
//（1）用字符数组，不用strcat函数（即自己编写一个具有strcat函数功能的函数）；
#include <iostream>
using namespace std;
int main()
{
char s1[80], s2[40];
int i = 0, j = 0;
cout << "input string1:";
cin >> s1;
cout << "input string2:";
cin >> s2;
while (s1[i] != '\0')
i++;
while (s2[j] != '\0')
s1[i++] = s2[j++];
s1[i] = '\0';
cout << "The new string is: " << s1 << endl;
return 0;
}
//（2）用标准库中的strcat函数
#include <iostream>
using namespace std;
int main()
{
char s1[80], s2[40];
cout << " input string1:";
cin >> s1;
cout << " input string2:";
cin >> s2;
strcat(s1, s2);
cout << "?The new string is:" << s1 << endl;
return 0;
}
//（3）用string方法定义字符串变量
#include <iostream>
#include <string>
using namespace std;
int main()
{
string s1 = "week", s2 = "end";
cout << "s1=" << s1 << endl;
cout << "s2=" << s2 << endl;
s1 = s1 + s2;
cout << "The new string is:" << s1 << endl;
return 0;
}运行结果：
//input string1：week↙
//input string2 : end↙
//The new string is : weekend
【解】
#include <iostream>
#include <string>
using namespace std;
int main()
{
const int n = 5;
int i, j;
string str[n], temp;
cout << "please input strings:" << endl;
for (i = 0; i < n; i++)
cin >> str[i];
for (i = 0; i < n - 1; i++)
for (j = 0; j < n - i - 1; j++)
if (str[j] > str[j + 1])
{
temp = str[j]; str[j] = str[j + 1]; str[j + 1] = temp;
}
cout << endl << "sorted strings:" << endl;
for (i = 0; i < n; i++)
cout << str[i] << endl;
return 0;
}运行结果：
//please input strings : （要求输入各字符串）
//China↙
//Japan↙
//Canada↙
//India↙
//Korea↙
//
//sorted strings : （已按要求排好序的字符串）
//
//Canada
//China
//India
//Japan
//Korea
【解】
#include <iostream>
#include <string>
using namespace std;
int main()
{
const int n = 5;
string str;
for (int i = 0; i < n; i++)
{
cout << "please input string:";
cin >> str;
if (str[0] == 'A')
cout << str << endl;
}
return 0;
}运行结果：
//please input string ?China↙?? ?（输入一个字符串）
//please input string : Again↙?? ?（输入一个字符串）
//Again?? ?（字符串以'A'开头, 输出此字符串）
//please input string : program↙?? ?（输入一个字符串）
//please input string : Abort↙?? ?（输入一个字符串）
//Abort?? ?（字符串以'A'开头, 输出此字符串）
//please input string : word↙?? ?（输入一个字符串）
【解】
//（1）用字符数组方法
#include <iostream>
using namespace std;
int main()
{
const int n = 10;
int i;
char a[n], temp;
cout << "please input a string:";
for (i = 0; i < n; i++)
cin >> a[i];
for (i = 0; i < n / 2; i++)
{
temp = a[i]; a[i] = a[n - i - 1]; a[n - i - 1] = temp;
} //对称位置元素交换
for (i = 0; i < n; i++)
cout << a[i];
cout << endl;
return 0;
}
//（2）用string方法
#include <iostream>
#include <string>
using namespace std;
int main()
{
string a;
int i, n;
char temp;
cout << "please input a string:";
cin >> a;
n = a.size(); //计算字符串长度
for (i = 0; i < n / 2; i++)
{
temp = a[i]; a[i] = a[n - i - 1]; a[n - i - 1] = temp;
}
cout << a << endl;
return 0;
}运行结果：
//please input a string : abcdefghij↙
//jihgfedcba
【解】
#include <iostream>
#include <string>
using namespace std;
const int n = 10;
string name[n]; //定义姓名数组
int num[n], score[n]; //定义学号和成绩数组
int main()
{
int i;
void input_data();
input_data();
cout << endl << "The list failed:" << endl;
for (i = 0; i < n; i++)
if (score[i] < 60)
cout << name[i] << " " << num[i] << " " << score[i] << endl;
return 0;
}
void input_data()
{
int i;
for (i = 0; i < n; i++)
{
cout << "input name,number and score of student " << i + 1 << ":";
cin >> name[i] >> num[i] >> score[i];
}
}运行结果：
//input name, number and score of student 1:Wang 101 78↙ ? ? ? （输入10个学生资料）
//input name, number and score of student 2 : Fun 102 67↙
//input name, number and score of student 3 : Tan 104 98↙
//input name, number and score of student 4 : Li 106 67↙
//input name, number and score of student 5 : Zheng 108 56↙
//input name, number and score of student 6 : Ling 110 77↙
//input name, number and score of student 7 : Chen 112 96↙
//input name, number and score of student 8 : Song 114 78↙
//input name, number and score of student 9 : Xue 116 99↙
//input name, number and score of student 10 : Zhang 118 50↙
//
//The list failed : （输出不及格学生名单）
//Zheng 108 56
//Zhang 118 50