C++中的字符转换 to_string、sto

1.数字转字符串 to_string

将数字转换为字符串

string to_string(int val);
string to_string(long val);
string to_string(long long val);
string to_string(unsigned val);
string to_string(unsigned long val);
string to_string(unsigned long long val);
string to_string(float val);
string to_string(double val);
string to_string(long double val);

int i = 10086;
double d = 3.1415926;
string s1 = to_string(i);
string s2 = to_string(d);
cout << s1 << endl;//10086
cout << s2 << endl;//3.1415926

2.字符串转数字 sto

将字符串转换为数字

参数：

str是需要转换的字符串；idx是需要转换的起始位置；base是确定转换为多少进制数

int stoi(const string & str, size_t * idx = 0, int base = 10);
long stol(const string & str, size_t * idx = 0, int base = 10);
unsigned long stoul(const string & str, size_t * idx = 0, int base = 10);
long long stoll(const string & str, size_t * idx = 0, int base = 10);
unsigned long long stoull(const string & str, size_t * idx = 0, int base = 10);
float stof(const string & str, size_t * idx = 0);
double stod(const string & str, size_t * idx = 0);
long double stold(const string & str, size_t * idx = 0);

string s1("10086");
int i = stoi(s1);
cout << i << endl;//10086

string s2("3.1415926");
double d = stod(s2);
cout << s2 << endl;//3.1415926