program8.cpp

一个很小的程序,可以进行字符串比较,适合初学者学习,很容易读懂的

#include"iostream.h"
class string
{
private:
	char *s;
public:
	string()
	{
		s=NULL;
	}
	string(char * const S)
	{
		s=S;
	}
	friend const int operator ==(string & a,string & b);
};
const int operator ==(string & a,string & b)
{
	if(a.s==NULL||b.s==NULL)
		return 999;
	while(*(a.s)!='\0' && *(b.s)!='\0' && *(a.s)==*(b.s))
	{
		a.s++;
		b.s++;
	}
	if(*(a.s)=='\0'||*(b.s)=='\0')
		return 0;
	else if(*(a.s)>*(b.s))
		return 1;
	else
		return -1;
	cout<<a.s;
	return 1;
}
void main()
{
	string a,b;
	char s1[40];
	char s2[40];
	int f;
	cin>>s1;
	cin>>s2;
	a=s1;
	b=s2;
	f=a==b;
	if(f==0)
		cout<<"相等.\n";
	else if(f<0)
		cout<<"字符串1小于字符串2.\n";
    else if(f!=999)
		cout<<"字符串1大于字符串2.\n";
	else
		cout<<"字符串为空，比较无效!\007\n";
}