C++ 练气期之细聊字符串

int myChar='A';
cout<<myChar; 
//输出：65

char myChar=97;
cout<<myChar; 
//输出：a

char myChar='B';
char myChar_='A';
int res=myChar+myChar_;
cout<<"加操作："<<res<<endl; 
res=myChar-myChar_;
cout<<"减操作："<<res<<endl;
res=myChar*myChar_;
cout<<"乘操作："<<res<<endl;  
res=myChar/myChar_;
cout<<"除操作："<<res<<endl; 
bool is=myChar>myChar_;
cout<<"关系操作："<<is<<endl;

加操作：131
减操作：1
乘操作：4290
除操作：1
关系操作：1

char myChar='A';

char myStr[5]= {'H','E','L','L','O'};
cout<<myStr<<endl;

char myStr[6]= {'H','E','L','L','O','\0'};
cout<<myStr<<endl;
//输出结果：HELLO

char myStr[6]= {'H','E','L','\0','O','\0'};
cout<<myStr<<endl;
//输出结果：HEL

char myStr[3]= {'H','E','L','L','O','\0'};
cout<<myStr<<endl;

char myStr[]= {'H','E','L','L','O','\0'};
cout<<myStr<<endl;

char myStr[6]= {'H','E','L','L','O','\0'};
for(int i=0;i<6;i++){
 cout<<myStr[i]<<endl;
}

H
E
L
L
O

char myStr[8]= {'H','E','L','L','O','\0','M','Y'};
for(int i=0;i<8;i++){
 cout<<myStr[i]<<endl;
}

H
E
L
L
O

M
Y

char myStr[8]= {'H','E','L','L','O','\0','M','Y'};
cout<<"数组的长度:"<<sizeof(myStr)<<endl;
for(int i=0;i<sizeof(myStr);i++){
 cout<<myStr[i]<<endl;
}

数组的长度:8
H
E
L
L
O

M
Y

char myStr[8]="HELLO";
cout<<myStr<<endl;
//输出结果：HELLO

char myStr[6]="HELLO";
cout<<myStr<<endl;
//输出：HELLO

char myStr[6]="HELLO";
for(int i=0;i<sizeof(myStr);i++){
 cout<<myStr[i]<<endl;
}

char myStr[6]="HELLO";
myStr[0]="S";

char myStr[6]="HELLO";
char myStr_[6];
//错误
myStr_=myStr;

#include <iostream>
#include <cstring>
using namespace std;
int main(int argc, char** argv) {
 char myStr[6]="HELLO";
 char myStr_[6];
 strcpy(myStr_,myStr);
 cout<<myStr_<<endl;
 return 0;
}

char myStr[10]="HELLO";
cout<<strlen(myStr)<<endl;
//输出结果：5

char myStr[10]="HEL\0LO";
cout<<sizeof(myStr)<<endl;
cout<<strlen(myStr)<<endl;

10 
3

char myStr[10]="HEL\0LO";
cout<<strlen(myStr)<<endl;

cout<<"this is a test" "hello world"; 
//输出：this is a testhello world

#include <iostream>
#include <cstring>
using namespace std;
int main(int argc, char** argv) {
 char names[10]="Hello";
 char address[10]="changsha";
 strcat(names,address);
 cout<<names; 
 return 0;
}
//输出：Hellochangsha

#include <iostream>
#include <cstring>

using namespace std;
int main(int argc, char** argv) {
 char names[10]="zs";
 char names_[10]="ls";
 cout<<strcmp(names,names_); 
 return 0;
}
//输出结果：1

#include <iostream>
#include <cstring>
using namespace std;
int main(int argc, char** argv) {
 char srcStr[15]="Hello World";
 char subStr[5]="llo";
 cout<<strstr(srcStr,subStr); 
 return 0;
}
//输出：llo World

//空字符串
string str1;
//字符串常量直接赋值
string str2="Hello";
string str3 {"this"};
string str4("Hi");

string str="中国人";
cout<<str<<endl;
//输出：中国人

string str="Hello World";
cout<<str.size()<<endl;
cout<<str.length()<<endl;
//是否为空
cout<<str.empty()<<endl;
//能存储的最大长度 
cout<<str.max_size()<<endl;
//容量 
cout<<str.capacity()<<endl; 

11
11
0
4611686018427387897
11

string str="Hello World";
str.clear();
cout<<str<<endl;
//没有任何内容输出

string str="Hello World";
string str_="Hi";
//第一个参数指定插入位置，第二参数指定需要插入的字符串
str.insert(3,str_);
cout<<str<<endl;
//输出结果：HelHilo World

string str="Hello World";
//第一个参数：指定删除的起始位置，第二个参数：指定删除的结束位置
string str_= str.erase(1,3);
cout<<str_<<endl;
//输出：Ho World

string str="Hello World";
//只能追加字符串，不能追加字符
str.append("OK");
cout<<str<<endl;
//只能以字符为单位追加
str.push_back('O');
cout<<str<<endl;
//输出结果：
//Hello WorldOK
//Hello WorldOKO

string str="Hello World";
str.pop_back();
cout<<str<<endl;
//输出结果：Hello Worl

string str="Hello World";
string str_="Hello";
int res= str.compare(str_);
//返回值的语义和 `strcmp`一样。

//源字符串
string foo("quuuux");
//目标字符串，数组形式
char bar[7];
//第一个参数，目标字符串，第二参数，向目标字符串复制多少
foo.copy(bar, sizeof bar);
bar[6] = '\0';
cout << bar << '\n';
//输出：quuuux

string str;
char bar[7];
cin>>str;
cin>>bar;
cout<<str<<endl;
cout<<bar<<endl;

char str[20];
cin.get(str,10);
cout<<str<<endl;
//输入：this is 输出：this is

char str[20];
cin.getline(str,10);
cout<<str<<endl;

char str[20];
char str_[20];
//第一次输入
cin.get(str,10);
cout<<str<<endl;
//第二次输入
cin.get(str_,10);
cout<<str_<<endl;

char str[20];
char str_[20];
cin.get(str,10);
cout<<str<<endl;
//不带参数的 get 方法可以清除数据
cin.get(); 
cin.get(str_,10);
cout<<str_<<endl;

char str[20];
char str_[20];
//第一次输入
cin.getline(str,10);
cout<<"str:"<<str<<endl;
//第二次输入
cin.getline(str_,10);
cout<<"str_:"<<str_<<endl;

//字符串对象
string str;
//第一个参数：cin对象  第二个参数：字符串对象
getline(cin,str);
cout<<str<<endl;