[Conversion between string, const char*, char* and int]

Summary: Record the conversion methods between string type, int type, const char type and char type in C++.

1. Interchange between string and const char*

1.string --> const char*

//1
string str = "asf";
const char* ch = str.c_str();
//2
string str = "asf";
const char* ch = str.data();

2. Convert between const char* and char*

1.const char* --> char*

//1
memcpy(pCh,str.c_str(),sizeof(str));

2.char* --> const char*

//直接赋值

3. Convert between string and int

1.string --> int

//1
string str = "234";
int num = atoi(str.c_str());
//2
num = stoi(str);

2.int --> string

int num = 9998;
string str = to_string(num);