String-Char的转换（基础知识复习）

#include<iostream>
#include<string.h>
using namespace std;
int main(){
  //1.string->char*
  string str = "hello";
  const char* p = str.data();
  char *p1=(char*)str.data();
  cout<<p<<endl;
  cout<<p1<<endl;
  
  //2.string->char[]
  string p2="hello world";
  char q[20];
  int i=0;
  // for( i=0;i<p.length();i++){或
  for( i=0;i<str.length();i++){
    q[i]=p[i];
  } 
  q[i]='\0';
  cout<<q<<endl;
  
  //3.char *->string
  char *p3="Hello world";
  string  s=p;
  cout<<s<<endl;
  
  //4.char[]->string
  char str2[6]="123\0";
  string str=str2;
  cout<<str<<endl;
}