C++: string 转 int ；string转float；int 转string；double转char*

1、string转int

std::string str1="700"
 int bid_v1 = atoi(str1.c_str());

2、string转float

std::string str2="6.78"
float bid_p1 = atof（str2.c_str());

3、int 转string

int n =789;
char t[256];
sprintf(t, "%d", n);
string s(t)

4、double转char*

char str[255];
sprintf(str, "%f", 10.8); //将10.8转为字符串