One, based on C++11 standard
Header file: #include <string>
function:
1.1 Value to string
to_string(val): Other types can be converted to string.
1.2 string conversion value
stoi(s, p, b): string to int
stol(s, p, b): string to long
stod(s, p, b)：string转double
stof(s, p, b): string to float
stold(s, p, b)：string转long dluble
stoul(s, p, b), stoll(s, p, b), stoull(s, p, b)等。
Remarks: return the value of the starting substring of s (a string representing the content of an integer); b represents the base used for conversion, and the default is 10 (representing decimal); p is a pointer to size_t, which is used to store the first non- The subscript of a numeric character, p is 0 by default, that is, the function does not return the subscript.
1 void testTypeConvert()
2 {
3 //int --> string
4 int i = 5;
5 string s = to_string(i);
6 cout << s << endl;
7 //double --> string
8 double d = 3.14;
9 cout << to_string(d) << endl;
10 //long --> string
11 long l = 123234567;
12 cout << to_string(l) << endl;
13 //char --> string
14 char c = 'a';
15 cout << to_string(c) << endl; //自动转换成int类型的参数
16 //char --> string
17 string cStr; cStr += c;
18 cout << cStr << endl;
19
20
21 s = "123.257";
22 //string --> int;
23 cout << stoi(s) << endl;
24 //string --> long
25 cout << stol(s) << endl;
26 //string --> float
27 cout << stof(s) << endl;
28 //string --> doubel
29 cout << stod(s) << endl;
30 }
Second, the version before C++11
The C++11 standard did not provide a corresponding method to call before, so you have to write the conversion method yourself. The code is as follows:
To convert from other types to string , define a method of a template class.
Convert from string to other types and define multiple overloaded functions.
1 #include <strstream>
2 template<class T>
3 string convertToString(const T val)
4 {
5 string s;
6 std::strstream ss;
7 ss << val;
8 ss >> s;
9 return s;
10 }
11
12
13 int convertStringToInt(const string &s)
14 {
15 int val;
16 std::strstream ss;
17 ss << s;
18 ss >> val;
19 return val;
20 }
21
22 double convertStringToDouble(const string &s)
23 {
24 double val;
25 std::strstream ss;
26 ss << s;
27 ss >> val;
28 return val;
29 }
30
31 long convertStringToLong(const string &s)
32 {
33 long val;
34 std::strstream ss;
35 ss << s;
36 ss >> val;
37 return val;
38 }
39
40 void testConvert()
41 {
42 //convert other type to string
43 cout << "convert other type to string:" << endl;
44 string s = convertToString(44.5);
45 cout << s << endl;
46 int ii = 125;
47 cout << convertToString(ii) << endl;
48 double dd = 3.1415926;
49 cout << convertToString(dd) << endl;
50
51 //convert from string to other type
52 cout << "convert from string to other type:" << endl;
53 int i = convertStringToInt("12.5");
54 cout << i << endl;
55 double d = convertStringToDouble("12.5");
56 cout << d << endl;
57 long l = convertStringToLong("1234567");
58 cout << l << endl;
59 }