如何从字符串计算浮点值

# 使用内置的float()函数
string_value = "3.14"
float_value = float(string_value)
print(float_value)  # 输出: 3.14

// 使用Double.parseDouble()方法
String stringValue = "3.14";
double floatValue = Double.parseDouble(stringValue);
System.out.println(floatValue);  // 输出: 3.14

// 使用parseFloat()函数
let stringValue = "3.14";
let floatValue = parseFloat(stringValue);
console.log(floatValue);  // 输出: 3.14

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

int main() {
    std::string stringValue = "3.14";
    std::stringstream ss(stringValue);
    double floatValue;
    ss >> floatValue;
    std::cout << floatValue << std::endl;  // 输出: 3.14
    return 0;
}

try:
    string_value = "3.14abc"
    float_value = float(string_value)
except ValueError as e:
    print(f"Error: {e}")

try {
    String stringValue = "3.14abc";
    double floatValue = Double.parseDouble(stringValue);
} catch (NumberFormatException e) {
    System.out.println("Error: " + e.getMessage());
}

from decimal import Decimal

string_value = "3.141592653589793"
float_value = Decimal(string_value)
print(float_value)  # 输出: 3.141592653589793