【学习C++】C++ Primer Plus （第六版）第八章编程练习1-7

1.

#include <iostream>
#include <string>
using namespace std;
void priStr(char *);
void priStr(char *, int n);
static int i = 1;
int main()
{
	char a[10] = "liujiayu";
	priStr(a);
	for (int i = 1; i < 4; i++){
		priStr(a, i);
	}
	cin.get();
	return 0;

}
void priStr(char *a){
	cout << a << endl;
}
void priStr(char *a, int n){
	if (n != 0){
		for (int j = 0; j < i; j++)
			cout << a << endl;
		i++;
	}
	else
		cout << "input error" << endl;
}

2.

#include <iostream>
#include <string>
using namespace std;
struct CandyBar{
	char * brandName;
	double weight;
	int cal;
};
void setCandy(CandyBar &a, char *n="Millennium Munch", double w=2.85, int c=350);
void showCandy(const CandyBar &);
int main()
{
	CandyBar candy;
	setCandy(candy, "ljy", 3.8, 400);
	showCandy(candy);
	setCandy(candy);
	showCandy(candy);
	cin.get();
	return 0;
}
void setCandy(CandyBar &a, char *n, double w, int c){
	a.brandName = n;
	a.weight = w;
	a.cal = c;
}
void showCandy(const CandyBar &a){
	cout << a.brandName << endl;
	cout << a.weight << endl;
	cout << a.cal << endl;
}

3.

#include <iostream>
#include <string>
using namespace std;
char * l_u(string &);
int main()
{
	cout << "Enter a string(q to quit): ";
	string str;
	while (getline(cin, str)){
		if (str != "q"){
			cout << l_u(str)<<endl;
			delete [] l_u(str);
			cout << "Next string(q to quit):";
		}
		else
			break;
	}
	cout << "Bye."<<endl;
	cin.get();
	return 0;
}
char * l_u(string &str){
	int n = str.size();
	char *s = new char[n+1];
	for (int i = 0; i < n; i++){
		s[i] = toupper(str[i]);
	}
	s[n] = '\0';
	return s;
}

4.

#include <iostream>
#include <cstring>
using namespace std;
struct stringy{
	char * str;
	int ct;
};
void set(stringy &, char *);
void show(const stringy &, int n = 1);
void show(const char *, int n = 1);
int main()
{
	stringy beany;
	char testing [] = "Reality isn't what it used to be.";
	set(beany, testing);
	show(beany);
	show(beany, 2);
	testing[0] = 'D';
	testing[1] = 'u';
	show(testing);
	show(testing, 3);
	show("Done!");
	cin.get();
	return 0;
}
void set(stringy &str, char *ch){
	int strl = strlen(ch);
	char *s = new char [strl+1];
	for (int i = 0; i < strl; i++){
		s[i] = ch[i];
	}
	s[strl] = '\0';
	str.str = s;
	str.ct = 2;
}
void show(const stringy &s, int n){
	for (int i = 0; i < n; i++){
		cout << s.str << endl;
	}
}void show(const char *c, int n){
	for (int i = 0; i < n; i++){
		cout << c << endl;
	}
}

5.

#include <iostream>
#include <string>
using namespace std;
template<typename T>
T max5(T *a);
int main()
{
	int a[5] = { 0, 1, 2, 3, 4 };
	double b[5] = { 0.0, 1.0, 2.0, 3.0, 4.9 };
	cout << max5(a) << endl;
	cout << max5(b) << endl;
	cin.get();
	return 0;
}
template<typename T>
T max5(T *a){
	T temp=a[0];
	for (int i = 1; i < 5; i++){
		if(a[i]>temp) 
			temp = a[i];
	}
	return temp;
}

6.

#include <iostream>
#include <string>
using namespace std;
template<typename T>
T maxn(T a[],int n);
template <> char* maxn<char *>(char * a[], int n);
int main()
{
	int a[6] = { 0, 1, 2, 3, 4,5 };
	double b[4] = { 0.0, 1.0, 2.0, 3.9 };
	char* c[5] = { "liu", "jia", "yu", "good", "girl" };
	cout << maxn(a,6) << endl;
	cout << maxn(b,4) << endl;
	cout << maxn(c, 5) << " at " << static_cast<const void *>(maxn(c, 5)) << endl;
	cin.get();
	return 0;
}
template<typename T>
T maxn(T *a,int n){
	T temp=a[0];
	for (int i = 1; i < n; i++){
		if(a[i]>temp) 
			temp = a[i];
	}
	return temp;
}
template <> char* maxn<char *>(char * a[], int n){
	int temp = strlen(a[0]);
	int l=0;
	for (int i = 1; i < n; i++){
		if (strlen(a[i]) > temp){
			temp = strlen(a[i]);
			l = i;
		}
	}
	return a[l];
}

7.

#include <iostream>
using namespace std;
template <typename T>
void SumArray(T arr[], int n);

template <typename T>
void SumArray(T * arr [], int n);
struct debts{
	char name[50];
	double amount;
};
int main()
{
	int things[6] = { 13, 31, 103, 301, 310, 130 };
	debts mr_E[3] = { { "Ima Wolfe", 2400.0 }, { "Ura Foxe", 1300.0 }, { "Iby Stout", 1800.0 } };
	double * pd[3];
	for (int i = 0; i < 3; i++)
		pd[i] = &mr_E[i].amount;
	cout << "Counting Mr.E's counts of things:\n";
	SumArray(things, 6); 
	cout << "Counting Mr.E's debts:\n";
	SumArray(pd, 3);
	cin.get();
	return 0;
}
template <typename T>
void SumArray(T arr [], int n){
	cout << "Template A\n";
	T sum=arr[0];
	for (int i = 1; i < n; i++){
		sum += arr[i];
	}
	cout << sum<<endl;
}
template <typename T>
void SumArray(T * arr [], int n){
	cout << "Template B\n";
	T sum = *arr[0];
	for (int i = 1; i < n; i++){
		sum += *arr[i];
	}
	cout << sum << endl;
}