C++字串型數字與int型數字的轉換
阿新 • • 發佈:2020-08-14
1、string-->int
1.1 C++風格--流
1 include<sstream> 2 3 stringstream stream; 4 int num = 0; 5 string text("123"); 6 stream << text; 7 stream >> num; 8 stream.clear();//轉換後字串還保留在流中,需使用手動清空
1.2 C風格--atoi()函式
int number = 0; string text = "123"; number = atoi(text.c_str());
2、int-->string
2.1 to_string()函式
string num1 = "1234" + to_string(456);
to_string()函式的實現如下:
1 //實現to_string函式 2 #include<iostream> 3 #include<string> 4 using namespace std; 5 #define max 100 6 string to_String(int n) 7 { 8 int m = n; 9 char s[max]; 10 char ss[max]; 11 int i=0,j=0;12 if (n < 0)// 處理負數 13 { 14 m = 0 - m; 15 j = 1; 16 ss[0] = '-'; 17 } 18 while (m>0) 19 { 20 s[i++] = m % 10 + '0'; 21 m /= 10; 22 } 23 s[i] = '\0'; 24 i = i - 1; 25 while (i >= 0) 26 { 27 ss[j++] = s[i--]; 28 }29 ss[j] = '\0'; 30 return ss; 31 } 32 33 int main() 34 { 35 cout << "請輸入整數:"; 36 int m; 37 cin >> m; 38 string s = to_String(m) + "abc"; 39 cout << s << endl; 40 system("pause"); 41 return 0; 42 }
2.2 字元流
1 int aa = 30; 2 stringstream ss; 3 ss<<aa; 4 string s1 = ss.str(); 5 cout<<s1<<endl; // 30