Question

我创建了我的第一个win32表单。我有一个错误，当消息框中显示一个小数作为输出时，它会打印到大约第10个小数位。在控制台程序中，我可以使用precision（2）命令将小数位设置为2个位置，但我无法在win32中找到它。这是代码：

private: System::Void button1_Click(System::Object^  sender, System::EventArgs^  e) {

    if (this->comboBox1->SelectedIndex == 0 && this->radioButton1->Checked == true) {
        double a = Convert::ToDouble(this->textBox1->Text->Trim());
        double b = Convert::ToDouble(this->textBox2->Text->Trim());

        double sum = (b - a) * 100;


        MessageBox::Show("$" + sum);
    }

    else if (this->comboBox1->SelectedIndex == 0 && this->radioButton2->Checked == true) {
        double a = Convert::ToDouble(this->textBox1->Text->Trim());
        double b = Convert::ToDouble(this->textBox2->Text->Trim());

        double sum = (a-b) * 100;


        MessageBox::Show("$" + sum);
    }

    if (this->comboBox1->SelectedIndex == 1 && this->radioButton1->Checked == true) {
        double a = Convert::ToDouble(this->textBox1->Text->Trim());
        double b = Convert::ToDouble(this->textBox2->Text->Trim());

        double sum = (b - a) * 50;


        MessageBox::Show("$" + sum);
    }

    else if (this->comboBox1->SelectedIndex == 1 && this->radioButton2->Checked == true) {
        double a = Convert::ToDouble(this->textBox1->Text->Trim());
        double b = Convert::ToDouble(this->textBox2->Text->Trim());

        double sum = (a - b) * 50;

        MessageBox::Show("$" + sum);
    }

    if (this->comboBox1->SelectedIndex == 2 && this->radioButton1->Checked == true) {
        double a = Convert::ToDouble(this->textBox1->Text->Trim());
        double b = Convert::ToDouble(this->textBox2->Text->Trim());

        double sum = (b - a) * 50;


        MessageBox::Show("$" + sum);
    }

    else if (this->comboBox1->SelectedIndex == 2 && this->radioButton2->Checked == true) {
        double a = Convert::ToDouble(this->textBox1->Text->Trim());
        double b = Convert::ToDouble(this->textBox2->Text->Trim());

        double sum = (a - b) * 50;

        MessageBox::Show("$" + sum);
    }   


}

Answer 1

如果您想要字符串转换的特定格式，则需要告诉它使用哪种格式。标准数字格式列在MSDN。

为了将double转换为带有两位小数的字符串，您可以使用定点格式。

sum.ToString("F2")

但是，由于您在那里获得了美元符号，因此您转换的价值似乎是美元。在这种情况下，我们可以做得更好，并使用适当的货币格式。这将使用您当前文化的货币符号，或者您可以指定要使用的文化。

sum.ToString("C")

在win32消息框中将decimal设置为精度2个位置

1 个答案: