Java程序猿学习C++之字符串

Posted 2020-06-24 Brenda

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

int my_len(const char *str)
{
	int len = 0;
//	while (*str != '\0')
//	{
//		++len;
//		++str;
//	}

	while (*(str++) != '\0')
	{
		++len;
	}


	return len;
}

void my_cpy(char *dst,const char *src)
{
	while (*src != '\0')
	{
		*dst = *src;
		++dst;
		++src;
	}
}

int main()
{
	char str1[] = "abc";//后面自己主动加上'\0'
	char str2[] = { 'a', 'b', 'c' };//后面不会自己主动加上个'\0'，作为字符串会一直找到'\0'标志
	char str3[] = { 'a', 'b', 'c' ,'\0'};
	char str4[10] = "abc";

	//              4                      3                      4                      10
	cout << sizeof(str1) << "," << sizeof(str2) << "," << sizeof(str3) << "," << sizeof(str4) << endl;
	//              3                      15                      3                      3
	cout << strlen(str1) << "," << strlen(str2) << "," << strlen(str3) << "," << strlen(str4) << endl;
	cout << my_len(str1) << "," << my_len(str2) << "," << my_len(str3) << "," << my_len(str4) << endl;

	//       abc       abc烫烫烫烫蘟bc    abc            abc
	cout << str1 << "," << str2 << "," << str3 << "," << str4 << endl;

	//字符串赋值
	//str1 = str2;// 错误。数组名是地址常量
	//str1 = "hello";// 错误。数组名是地址常量
	strcpy(str4,str1);

	//strcmp(str1,str2);字符串比較
	//strcat(str3,str2);字符串拼接，必须推断空间是否够

	//字符串切割
	char str[] = "this is a test";
	char *token = strtok(str, " ");
	while (token != NULL)
	{
		cout << token << endl;
		token = strtok(NULL," ");
	}

	return 0;
}

c++风格字符串

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

int main()
{
	string str1 = "hello";
	string str2 = "abc";
	string str3 = "abc";

	//拷贝赋值
	str3 = str1;
	cout << str1 << "," << str3 << endl;

	//获取长度
	cout << str1.length() << endl;

	//字符串的比較
	str1.compare(str3);

	//字符串拼接
	str3 += str2;

	//字符串切割
	string str4 = "this is a test";
	//转换为c风格的string
	//char *token = strtok((char *)str4.c_str(), " ");//强制类型转换
	char *token = strtok(const_cast<char *>(str4.c_str()), " ");
	while (token != NULL)
	{
		cout << token << endl;
		token = strtok(NULL, " ");
	}

	//遍历字符串(string::size_type i = 0; i < str1.length();i++)
	for (string::size_type i = 0; i < str1.length(); i++)
	{
		cout << str1[i] << "-" ;
	}
	cout << endl;

	for (string::size_type i = 0; i < str1.length(); i++)
	{
		cout << str1.at(i) << "-";
	}
	cout << endl;

	for (string::iterator itr = str1.begin(); itr != str1.end();++itr)
	{
		cout << *itr << "-";
	}
	cout << endl;




	int cnt = 0;
	while (cnt < 50)
	{
		if (str1.size() == str1.capacity())
		{
			//cout << "hhh";
		}
		str1.push_back('*');
		cnt++;
		//cout << str1.size() << "," << str1.capacity() << endl;
	}


	str1.clear();
	if (str1.empty())
	{
		cout << "str1.empty";
	}

	return 0;
}