C++程序 求解答

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#include
int isPrime(int n) { int flag = 1; int i; for (i = 2; i <= sqrt(n); i++) { if (n % i == 0) { return 0; } } return flag;}
int getLeastPrimeFactor(int n) { int i; for (i = 2; i <= n / 2; i++) { if (isPrime(i)) { if (n % i == 0) { return i; } } } return n;}
int main() { int i, j; int bigNum[20]; int smallNum[20]; for (i = 0; i < 20; i++) { bigNum[i] = 21 + i; smallNum[i] = 1 + i; } for (i = 0; i < 20; i++) { while (smallNum[i] != 1) { int leastPrimeFactor = getLeastPrimeFactor(smallNum[i]); for (j = 0; j < 20; j++) { if (bigNum[j] % leastPrimeFactor == 0) { bigNum[j] = bigNum[j] / leastPrimeFactor; smallNum[i] = smallNum[i] / leastPrimeFactor; break; } } } } long long ans = 1; for (i = 0; i < 20; i++) { ans = ans * bigNum[i]; } printf("%lld\n", ans); return 0;}

/*
name : zhangsan, number = 1
name : Jenny, number = 2
name : Randy, number = 3
Press any key to continue
*/
#include <iostream>
#include <string.h>
using namespace std;

class Student {
static int number;
char name[20]; // string的实例是受保护的，所以用char []
// char *name;
public:
Student() {}
Student(const char *str) { strcpy(name,str); ++number; } // 转换构造函数
void set(const char *str) { strcpy(name,str); ++number; }
void show() const { cout<<"name : "<<name<<", number = "<<number<<endl; }
};

void fn() {
Student s1 = Student("Jenny");
Student s2;
s1.show();
s2.set("Randy");
s2.show();
}

int Student::number = 0; // 类的静态数据成员初始化，很奇怪的！

int main() {
Student s = Student("zhangsan");
s.show();
fn();
return 0;
}

#include<iostream>
#include<string>
using namespace std;

class Student{
static int number;
string name;
// char *name;
public:
void set(string str){
name=str;
++number;
}
void show(){
cout<<"The name is"<<name<<",the number is"<<number<<endl;
}
};

void fn(){

Student s1;
s1.set("Jenny");
Student s2;
s2.set("Randy");
s1.show();
}
int Student::number=0;

int main(){
Student s;
s.set("zhangsan");
fn();
s.show();
return 0;

}
问题比较多，主要是以下两个：
1.程序中要用到string类时，头文件应该是#include<string>
2.静态数据成员需要在类外初始化，就是这一句：int Student::number=0;
注意，在类外访问类的静态变量时，需要加Student::限定符。
还有，用了int main()时，要有返回值0.

#include<iostream>
#include<string>
//#include<string.h>
using namespace std;

class Student
{
static int number;
string name;
// char *name;
public:
void set(string str)
{
name=str;
++number;
}
void show()
{
cout<<"The name is"<<name.c_str()<<",the number is"<<number<<endl;
}
};

void fn()
{

Student s1;
s1.set("Jenny");
Student s2;
s2.set("Randy");
s1.show();
}

int main()
{
Student s;
s.set("zhangsan");
fn();
s.show();
return 0;
}
这样可以了！

添加一句初始化
可以在Class Student后面
int Student::number;
或者
int Student::number = 0;

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