[C++知识库]int同string互转

int同string互转

Ⅰ、to_string函数

c++11标准增加了全局函数std::to_string:

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);

Example：

1 // to_string example
2 #include // std::cout
3 #include // std::string, std::to_string
4
5 int main ()
6 {
7 std::string pi = “pi is " + std::to_string(3.1415926);
8 std::string perfect = std::to_string(1+2+4+7+14) + " is a perfect number”;
9 std::cout << pi << ‘\n’;
10 std::cout << perfect << ‘\n’;
11 return 0;
12 }
13 Output
14 pi is 3.141593
15 28 is a perfect number

二、string转换成int

Ⅰ、采用标准库中atoi函数,对于其他类型也都有相应的标准库函数，比如浮点型atof(),long型atol()等等

Example：

1 std::string str = “123”;
2 int n = atoi(str.c_str());
3 cout<<n; //123