空降
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1
void swap(int& x,int& y)
{//交换x和y
int temp = x;
x=y;
y =temp;
}
``
## <span id="2">2</span>
```C++
#include <iostream>
template<typename T,int n>
int count(const T(&a)[n], const T& value)
{
int sum = 0;
for (int i = 0; i != n; ++i)
if (a[i] == value)
++sum;
return sum;
}
int main()
{
int a[] = { 1,1,1,1,2,3,4,5,6,7 };
std::cout << count(a, 1) << std::endl;
return 0;
}
3
#include <iostream>
template<typename T,int n>
void fill(T(&a)[n], const T& value)
{
int start = 0;
int end = n;
for (; start != end; ++start)
a[start] = value;
}
int main()
{
int arr[]{ 1,2,3,4,5 };
fill(arr, 0);
for (auto i : arr)
std::cout << i << std::endl;
return 0;
}
4
#include <iostream>
template<typename T,int n>
T inner_product(const T(&a)[n],const T(&b)[n])
{
T sum = 0;
for (int i = 0; i != n; ++i)
sum += a[i] * b[i];
return sum;
}
int main()
{
using namespace std;
int a[] = { 1,2,3 };
int b[] = { 1,2,3 };
cout << inner_product(a, b) << endl;
return 0;
}
5
#include <iostream>
template<typename T,int n>
void iota(T(&a)[n],const T& value)
{
for (int i = 0; i != n; ++i)
a[i] = value + i;
}
int main()
{
using namespace std;
int a[] = { 1,2,3 };
iota(a, 4);
for (auto i : a)
cout << i << endl;
return 0;
}
6
#include <iostream>
template<typename T, int n>
bool is_sorted(const T(&a)[n])
{
int i = 0;
if (a[i] < a[i + 1])
{
for (i = 1; i != n - 1; ++i)
if (a[i] < a[i + 1])
continue;
else
return false;
}
else
{
for (i = 1; i != n - 1; ++i)
if (a[i] > a[i + 1])
continue;
else
return false;
}
return true;
}
int main()
{
using namespace std;
int a[] = { 1,2,3 };
int b[]{ 3,2,1 };
int c[]{ 2,1,3 };
cout << is_sorted(a) << endl;
cout << is_sorted(b) << endl;
cout << is_sorted(c) << endl;
return 0;
}
7
#include <iostream>
template<typename T, int n>
int mismatch(const T(&a)[n], const T(&b)[n])
{
for (int i = 0; i != n; ++i)
if (a[i] != b[i])
return i;
return -1;
}
int main()
{
using namespace std;
int a[] = { 1,2,3 };
int b[]{ 3,2,1 };
int c[]{ 1,2,4 };
cout << mismatch(a, b)<< endl;
cout << mismatch(a, c)<< endl;
return 0;
}
8
不同函数签名只由参数类型决定，它们的签名都是（int，int，int），
所以不具有不同签名。
9
(1)、调用int abc();
(2)、调用float abc();
(3)、报错：由于类型转换从两个float到 int和 int到 float是可能的。
(4)、报错：这里的参数类型为(double,double,double)，调用不明。
再则，double到int和float有可能编译出错。
10
#include <iostream>
int abc(int a,int b,int c)
{
if(a<0||b<0||c<0)
throw 1;
else if(a==0&&b==0&&c==0)
throw 2;
return a+b+c;
}
int main()
{
try
{
//std::cout<<abc(2,-1,4)<<std::endl;
std::cout<<abc(0,0,0)<<std::endl;
}
catch(int i)
{
std::cout<<i<<std::endl;
return 1;
}
return 0;
}
11
#include <iostream>
template<typename T,int n>
int count(const T(&a)[n], const T& value)
{
if(n<1)
throw "n must be >=1";
int sum = 0;
for (int i = 0; i != n; ++i)
if (a[i] == value)
++sum;
return sum;
}
int main()
{
int a[] = { 1,1,1,1,2,3,4,5,6,7 };
try
{
std::cout << count(a, 1) << std::endl;
}
catch(char* c)
{
std::cout<<c<<std::endl;
return 1;
}
return 0;
}
12
#include <iostream>
template<typename T>
void make2Array(T**& arr, int numberOfRows, int* rowSize)
{
arr = new T * [numberOfRows];
for (int i = 0; i < numberOfRows; ++i)
{
arr[i] = new T[rowSize[i]];
for (int j = 0; j < rowSize[i]; ++j)
arr[i][j] = rowSize[i];
}
}
int main()
{
int** a;
int rowSize[5]{ 1,2,3,4,5 };
make2Array(a, 5, rowSize);
for (int i = 0; i < 5; ++i)
for (int j = 0; j < rowSize[i]; ++j)
std::cout << a[i][j] << std::endl;
return 0;
}
13
#include <iostream>
#include <algorithm>
template<typename T>
void changeLength1D(T*& arr, int oldLength, int newLength)
{
if (newLength < 0)
throw std::runtime_error("new length must be >=0");
T* newArr = new T[newLength];
int length = std::min(oldLength, newLength);
std::cout << "length:" << length << std::endl;
std::copy(arr, arr + length, newArr);
delete[] arr;
arr = newArr;
}
int main()
{
int* arr = new int[3];
for (int i = 0; i != 3; ++i)
arr[i] = 0;
changeLength1D(arr, 2, 6);
for (int i = 0; i < 6; ++i)
std::cout << arr[i] << std::endl;
return 0;
}
14
#include <iostream>
#include <algorithm>
template<typename T>
void changeLength2D(T**& arr, int oldRow, int oldColumns,
int newRow, int newColumns)
{
if (newRow < 0 || newColumns < 0)
throw std::runtime_error("new length must be >=0");
T** newArr = new T * [newRow];
for (int i = 0; i != newColumns; ++i)
newArr[i] = new T[newColumns];
int row = std::min(oldRow, newRow);
int columns = std::min(oldColumns, newColumns);
for (int i = 0; i != row; ++i)
std::copy(arr[i], arr[i] + columns, newArr[i]);
for (int i = 0; i != oldRow; ++i)
delete[] arr[i];
delete[] arr;
arr = newArr;
}
int main()
{
int** arr = new int* [3];
for (int i = 0; i != 3; ++i)
arr[i] = new int[3];
for (int i = 0; i != 3; ++i)
for (int j = 0; j != 3; ++j)
arr[i][j] = j;
changeLength2D(arr, 3, 2, 3, 4);
for (int i = 0; i < 2; ++i)
for (int j = 0; j < 4; ++j)
std::cout << arr[i][j] << " ";
std::cout << std::endl;
return 0;
}
15
1)最大值：2^32-1 dollars and 99 cents 最小值：-max
2)最大值：2^31-1 dollars and 99 cents 最小值：-max
3)不超过：MAX_VALUE/100
16
//1)
void input()
{
cout << "Enter the currency amount with its sign dollars and cents" << endl;
signType thesign;
unsigned long thedollars;
unsigned int thecents;
cin >> thesign>>thedollars>>thecents;
// set the value
setValue(thesign,thedollars,thecents);
}
//2)
currency subtract(const currency& x)
{
currency result;
long a1,a2,a3;
a1=dollars*100+cents;
if(sign==minus) a1=-a1;
a2=x.dollars*100+x.cents;
if(x.sign==minus) a2=-a2;
a3=a1-a2;
if(a3<0){result.sign=minus;a3=-a3;}
else result.sign=plus;
result.dollars=a3/100;
result.cents=a3-result.dollars*100;
return result;
}
// 3)
currency percent(double x)
{
currency result;
long a1,a2;
a1=dollars*100+cents;
a2=(long)(a1*x/100);
result.sign=sign;
result.dollars=a2/100;
result.cents=a2-result.dollars*100;
return result;
}
// 4)
currency multiply(double x)
{
currency result;
long a1,a2;
a1=dollars*100+cents;
a2=a1*x;
result.sign=sign;
result.dollars=(long)a2/100;
result.cents=a2-result.dollars*100;
return result;
}
//5)
currency divide(double x)
{
currency result;
long a1,a2;
a1=dollars*100+cents;
a2=a1/x;
result.sign=sign;
result.dollars=(long)a2/100;
result.cents=a2-result.dollars*100;
return result;
}
17
void input()
{
cout << "Enter the currency amount as a real number" << endl;
double theValue;
cin >> theValue;
setValue(theValue);
}
currency subtract(const currency& x)
{
currency result;
result.amount = amount - x.amount;
return result;
}
currency percent(float x)
{
currency result;
result.amount = (long) (amount * x / 100);
return result;
}
currency multiply(float x)
{
currency result;
result.amount = (long) (amount * x);
return result;
}
currency divide(float x)
{
currency result;
result.amount = (long) (amount / x);
return result;
}
18
此时你最不想看见的字是什么？没错，略！
19
#include <iostream>
int factorial(int n)
{
if (n <= 1)
return 1;
int fact = 2;
for (int i = 3; i <= n; ++i)
fact *= i;
return fact;
}
int main()
{
std::cout << factorial(5) << std::endl;
return 0;
}
20
//1)
#include <iostream>
int fibonacci(int n)
{
if (n == 0)
return 0;
else if (n == 1)
return 1;
else
return fibonacci(n - 1) + fibonacci(n - 2);
}
int main()
{
std::cout << fibonacci(5) << std::endl;
return 0;
}
//3)
#include <iostream>
int fibonacci(int n)
{
if (n == 0)
return 0;
else if (n == 1)
return 1;
else
{
int fib = 0;
int f0 = 0, f1 = 1;
for (int i = 2; i <= n; ++i)
{
fib = f0 + f1;
f0 = f1;
f1 = fib;
}
return fib;
}
}
int main()
{
std::cout << fibonacci(5) << std::endl;
return 0;
}
21
//3)
#include <iostream>
int fun(int n)
{
return (n & 1) ? fun(3 * n + 1) : n / 2;
}
int main()
{
std::cout << fun(5) << std::endl;
return 0;
}
//4)
#include <iostream>
int fun(int n)
{
return (n & 1) ? (3 * n + 1) / 2 : n / 2;
}
int main()
{
std::cout << fun(7) << std::endl;
return 0;
}
22
#include <iostream>
#include <algorithm>
int A(int i, int j)
{
if (i == 1 && j >= 1)
return std::pow(2, j);
else if (i >= 2 && j == 1)
return A(i - 1, 2);
else
return A(i - 1, A(i, j - 1));
}
int main()
{
std::cout << A(2, 2) << std::endl;
return 0;
}
23
#include <iostream>
int gcd(int x, int y)
{
if (x == 0)
return y;
else if (y == 0)
return x;
else
return gcd(y, x % y);
}
int main()
{
std::cout << gcd(20, 30) << std::endl;
return 0;
}
24
#include <iostream>
template<typename T,int n>
bool fun(const T(&a)[n], T x, int pos)
{
if (pos >= n)
pos = n - 1;
if (pos == -1)return false;
else if (a[pos] == x)return true;
else return fun(a, x, pos - 1);
}
int main()
{
int a[]{ 1,2,3,4,5 };
int x = 1;
std::cout << fun(a, x, 6) << std::endl;
return 0;
}
25
#include <iostream>
template<typename T>
void sg(T* a, int* mark, int b, int l)
{//a为集合元素，mark为标记数组，b为起点，l为元素个数
if (b == l)
{
std::cout << "{ ";
for (int i = 0; i < l; i++)
{
std::cout << mark[i];
/*if (mark[k] == 1)
std::cout << a[k];*/
}
std::cout << "}" << std::endl;
return;
}
mark[b] = 0;
sg(a, mark, b + 1, l);
mark[b] = 1;
sg(a, mark, b + 1, l);
}
int main()
{
int mark[3]{ 0,0,0 };
char a[3] = { 'a','b','c' };
sg(a, mark, 0, 3);
return 0;
}
26
#include <iostream>
void gc(int n)
{
if (n <= 0)
throw std::runtime_error("n >=0");
if (n == 1)
std::cout << 1 << ",";
else
{
gc(n - 1);
std::cout << n << ",";
gc(n - 1);
}
}
int main()
{
gc(3);
std::cout << std::endl;
return 0;
}
27
#include <iostream>
template<typename InputIt, typename T>
T accumulate(InputIt first, InputIt last, T init)
{
for (; first != last; ++first)
init += *first;
return init;
}
int main()
{
int arr[]{ 1,2,3,4,5 };
std::cout << accumulate(arr,arr+5,0) << std::endl;
return 0;
}
28
#include <iostream>
#include <algorithm>
template<typename InputIt, typename T,
typename BinaryOperation>
T accumulate(InputIt first, InputIt last,
T init, BinaryOperation op)
{
for (; first != last; ++first)
init = op(init, *first);
return init;
}
int main()
{
int arr[]{ 1,2,3,4,5 };
std::cout << accumulate(arr,arr+5,1,std::multiplies<int>()) << std::endl;
return 0;
}
29
#include <iostream>
#include <vector>
template<typename InputIt,typename OutputIt>
OutputIt myCopy(InputIt first, InputIt last,
OutputIt to_first)
{
for (; first != last; ++first)
*to_first = *first++;
}
int main()
{
std::vector<int> vi1{1, 2, 3};
std::vector<int> vi2(4, 0);
copy(vi1.begin(), vi1.end(), vi2.begin());
for (auto e : vi2)
std::cout << e << std::endl;
return 0;
}
30
#include <iostream>
#include <iterator>
#include <algorithm>
using namespace std;
template<typename T>
void permutations1(T list[], int k, int m)
{//程序1-32，递归函数生成排列
if (k == m - 1)
{
copy(list, list + m, ostream_iterator<T>(cout, " "));
cout << endl;
}
else
for (int i = k; i <= m - 1; i++)
{
swap(list[k], list[i]);
permutations1(list, k + 1, m);
swap(list[k], list[i]);
}
}
template<typename T>
void permutations2(T list[], int k, int m)
{//练习30
sort(list, list + m);
do {
copy(list, list + m, ostream_iterator<T>(cout, " "));
cout << endl;
} while (next_permutation(list, list + m));
}
template<typename T>
void permutations3(T list[], int k, int m)
{//练习31
T temp[3];
copy(list, list + m, temp);
do {
copy(list, list + m, ostream_iterator<T>(cout, " "));
cout << endl;
} while (next_permutation(list, list + m));
while (prev_permutation(temp, temp + m))
{
copy(temp, temp + m, ostream_iterator<T>(cout, " "));
cout << endl;
}
}
template<typename T>
void permutations4(T list[], int k, int m)
{//练习32
while (next_permutation(list, list + m)) {}
do {
copy(list, list + m, ostream_iterator<T>(cout, " "));
cout << endl;
} while (next_permutation(list, list + m));
}
int main()
{
char ch[]{ 'c','b','a' };
permutations1(ch, 0, 3);
cout << "-----------" << endl;
permutations2(ch, 0, 3);
cout << "-----------" << endl;
char ch3[]{ 'c','a','b' };
permutations3(ch3, 0, 3);
cout << "-----------" << endl;
char ch4[]{ 'c','a','b' };
permutations4(ch4, 0, 3);
return 0;
}
33
#include <iostream>
int main()
{
int arr[]{ 1,1,1,1,2,3,4 };
std::cout<<std::count(arr, arr + 7, 1) << std::endl;
return 0;
}
34
#include <iostream>
int main()
{
int arr[4]{ 0 };
std::fill(arr, arr + 4, 1);
for (auto e : arr)
std::cout << e << " ";
std::cout << std::endl;
return 0;
}
35
#include <iostream>
#include <numeric>
int main()
{
int a[]{ 1,2,3 };
int b[]{ 1,2,3,4 };
std::cout << std::inner_product(a, a + 3, b, 0) << std::endl;
return 0;
}
36
#include <iostream>
#include <numeric>
int main()
{
int arr[5]{ 0 };
std::iota(arr, arr + 5, 1);
for (auto e : arr)
std::cout << e << std::endl;
return 0;
}
37
#include <iostream>
#include <algorithm>
int main()
{
using namespace std;
int a[]{ 1,3,2,4,5 };
int b[]{ 1,2,3 };
int c[]{ 3,2,1 };
if (is_sorted(c, c + 3))
cout << "YES" << endl;
else
cout << "NO" << endl;
return 0;
}
38
#include <iostream>
#include <algorithm>
int main()
{
using namespace std;
int a[]{ 1,2,3,4 };
int b[]{ 1,2,4,3 };
cout << *(mismatch(a, a + 4, b).first) << endl;
cout << *(mismatch(a, a + 4, b).second) << endl;
return 0;
}
39
#include <iostream>
template<typename InputIt, typename T>
int count(InputIt first, InputIt last, T value)
{
int sum = 0;
for (; first != last; ++first)
if (*first == value)
sum += 1;
return sum;
}
int main()
{
int arr[]{ 1,1,1,1,2,3,4 };
std::cout << count(arr, arr + 7, 1) << std::endl;
return 0;
}
40
#include <iostream>
template<typename InputIt,typename T>
void fill(InputIt first, InputIt last, T value)
{
for (; first != last; ++first)
*first = value;
}
int main()
{
int arr[4]{ 0 };
fill(arr, arr + 4, 1);
for (auto e : arr)
std::cout << e << " ";
std::cout << std::endl;
return 0;
}
41
#include <iostream>
template<typename InputItL,typename InputItR,
typename T>
T inner_product(InputItL firstL, InputItL lastL,
InputItR firstR, T init)
{
for (; firstL != lastL; ++firstL, ++firstR)
init += (*firstL * *firstR);
return init;
}
int main()
{
int a[]{ 1,2,3 };
int b[]{ 1,2,3,4 };
std::cout << inner_product(a, a + 3, b, 0) << std::endl;
return 0;
}
42
#include <iostream>
template <typename ForwardIt, typename T>
void iota(ForwardIt first, ForwardIt last, T val)
{
for (; first != last; ++first, ++val)
*first = val;
}
int main()
{
int arr[5]{ 6 };
iota(arr, arr + 5, 1);
for (auto e : arr)
std::cout << e << std::endl;
return 0;
}
43
#include <iostream>
template<typename ForwardIt>
bool is_sorted(ForwardIt first, ForwardIt last)
{
if (first == last)
return true;
for (ForwardIt next = first; ++next != last;++first)
if (*next < *first)
return false;
return true;
}
int main()
{
int a[]{ 1,2,3,4,5 };
int b[]{ 5,4,3,2,1 };
std::cout << is_sorted(a, a + 5) << std::endl;
std::cout << is_sorted(b, b + 5) << std::endl;
return 0;
}
44
#include <iostream>
template<typename InputItL,typename InputItR>
std::pair<InputItL,InputItR>
mismatch(InputItL firstL, InputItL lastL, InputItR firstR)
{
while ((firstL != lastL) && (*firstL == *firstR))
++firstL, ++firstR;
return std::make_pair(firstL, firstR);
}
int main()
{
using namespace std;
int a[]{ 1,2,3,4 };
int b[]{ 1,2,4,3 };
cout << *(mismatch(a, a + 4, b).first) << endl;
cout << *(mismatch(a, a + 4, b).second) << endl;
return 0;
}
45
void outputRoots(const double& a, const double& b, const double& c)
{//计算和输出二次方程的根
double d = b * b - 4 * a * c; ①
if(d>0) {//两个实数根} ②
else if(d==0) {//两个根相同} ③
else {//复数共轭根} ④
}
语句覆盖:1+2，1+3，1+4
分支覆盖:d<0,d+0,d>0
从句覆盖:d<0,d+0,d>0
执行路径覆盖:1+2，1+3，1+4
46
int a[]{ 1,2,3 };
测试集：(a,3)
47
template<typename T>
T sum(T a[], int n)
{
T theSum = 0; ①
for (int i = 0; i < n; i++) ②
theSum += a[i]; ③
return theSum; ④
}
n<0:1,2,4
n=0:1,2,4
n=1:1,2,3,2,4
n=2:1,2,3,2,3,2,4
不能提供分支覆盖：只有一条执行路径
48
template<typename T>
T rSum(T a[], int n)
{
if(n>0) ①
return rSum(a,n-1)+a[n-1]; ②
return theSum; ③
}
n<0:1,3
n=0:1,3
n=1:1,2,1,3
n=2:1,2,1,2,1,3
不能提供分支覆盖：只有一条执行路径