【字符串、栈】单个char字符转为string表示

单个char转string

char x = 'a';
string c = string(1, x);

string转单个char

string s = "abc";
char x = s[0];

string转char[]（字符数组）

string s = "abc";
s.c_str();

（字符数组）char[]转string

//直接赋值即可
char s1[4] = "abc";
string s2 = s1;

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单个char转string例题

样例1
输入

{A3B1{C}3}3

输出

AAABCCCAAABCCCAAABCCC

说明：
(A3B1{C}3}3代表A字符重复3次, B字符重复1次,花括号中的C字符重复3次，最外层花括号中的AAABCCC重复3次。

C++代码

#include <iostream>
#include <stack>using namespace std;
using i64 = long long;const int N = 1e5 + 10;stack<string> stk;int main()
{ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);string s;cin >> s;for (int i = 0; i < s.size(); i++){char x = s[i];string c = string(1, x);if (c == "{" || isalpha(x))stk.push(string(1, x));else if (isdigit(x)){int j = i, num = 0;while (j < s.size() && isdigit(s[j])) j++;num = stoi(s.substr(i, j - i));string tmp = stk.top();stk.pop();string t;for (int i = 0; i < num; i++) t += tmp;stk.push(t);}else if (c == "}"){string t;while (stk.size() && stk.top() != "{"){t = stk.top() + t;stk.pop();}stk.pop(); // 弹出左括号stk.push(t);}}string res;while (stk.size()){res = stk.top() + res;stk.pop();}cout << res;return 0;
}