1.string转char
string pp = "dagah";
char p[8];
int i;
for( i=0;i<pp.length();i++)
p[i] = pp[i];
p[i] = '\0';
printf("%s\n",p);
cout<<p;
2.char*转string
string s;
char *p = "hello";//直接赋值
s = p;
3.string转char*
string str = "hello";
const char* p = str.data();