C++编程：tostring的多样用法

std::to_string 是 C++11 标准库中的一个函数，用于将数字类型（如 int、float、double 等）转换为字符串。以下是 std::to_string 的一些常见用法：

1. 将整数转换为字符串：

#include<iostream>
#include<string>

int main() {
    int num = 42;
    std::string str_num = std::to_string(num);
    std::cout << "Integer: "<< num << ", String: "<< str_num<< std::endl;
    return 0;
}

2. 将浮点数转换为字符串：

#include<iostream>
#include<string>

int main() {
    double num = 3.14159;
    std::string str_num = std::to_string(num);
    std::cout << "Double: "<< num << ", String: "<< str_num<< std::endl;
    return 0;
}

3. 将浮点数转换为固定小数位数的字符串：

#include<iostream>
#include <iomanip>
#include <sstream>
#include<string>

std::string to_string_with_precision(const double value, const int precision) {
    std::ostringstream out;
    out<< std::fixed<< std::setprecision(precision)<< value;
    return out.str();
}

int main() {
    double num = 3.14159;
    int precision = 2;
    std::string str_num = to_string_with_precision(num, precision);
    std::cout << "Double: "<< num << ", String (precision "<< precision << "): "<< str_num<< std::endl;
    return 0;
}

4. 将浮点数转换为科学计数法表示的字符串：

#include<iostream>
#include <iomanip>
#include <sstream>
#include<string>

std::string to_scientific_string(const double value, const int precision) {
    std::ostringstream out;
    out<< std::scientific<< std::setprecision(precision)<< value;
    return out.str();
}

int main() {
    double num = 3.14159;
    int precision = 2;
    std::string str_num = to_scientific_string(num, precision);
    std::cout << "Double: "<< num << ", Scientific String (precision "<< precision << "): "<< str_num<< std::endl;
    return 0;
}

这些示例展示了 std::to_string 和其他相关函数的多样用法。你可以根据需要调整代码以适应不同的场景。