C++字符串与整数的相互转换

• 整型转字符串：to_string(int val);
• 字符串转整型：stoi(string str);、stol、stoll

#include 
#include 
using namespace std;

int main(){
    
    int a = 1234;
    float b = 3.14159265;
    
    cout << "int to string: " << to_string(a) << endl;
    cout << "float to string: " << to_string(b) << endl;
    
    string str1 = "1234";
    string str2 = "3.14159";
    
    cout << "string to int: " << stoi(str1) << endl;
   //cout << "string to float: " << stoi(b) << endl;  //不可以转浮点数
    
    return 0;    
}
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【2023keep秋招笔试】输入一个整数，可以改变数字的顺序，但只能把两个数字呼唤，在只能交换1次或0次顺序的情况下，输出所能组成的最大值。

// Example program
#include 
#include 
#include 
using namespace std;

string str1  = "123";
string str2 = "321";

void swap(string &a,string& b){
    string temp =  a;
    a = b;
    b = a;
}

string maxNum;
int maxinumSwap(int num){
    string str = to_string(num);

    for(int i = 1;i < str.size();++i){
        if (str[i] > str[0])
            swap(str[i],str[0]);
    }
    return stoi(str);
}


int main()
{
    int num = 1434;
    cout <<  maxinumSwap(num) << endl;
    
    return 0;
}
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