我如何立即退出功能，例如我要检查是否有库存，如果有库存，则应下订单，否则，应显示错误消息，然后单击单击确定按钮，将返回到解决方案，而无需运行其他方法/功能。
我的代码如下：
private void CheckForInStockGoods()
{
using (SqlConnection con = new SqlConnection(constring))
{
con.Open();
string checkQuery = "select * from productsmarket_Table where productname like '" + product_search.Text + "%' ";
using (SqlCommand cmd = new SqlCommand(checkQuery, con))
{
try
{
using (SqlDataReader rd = cmd.ExecuteReader())
{
if (rd.Read())
{
int availableQty = Convert.ToInt32((rd["productQty"].ToString()));
if (availableQty == 0)
{
MessageBox.Show("You cannot Place This Order\n You appear to be out of stock!", "Out of Stock", MessageBoxButtons.OK, MessageBoxIcon.Error);
return;
}
}
}
}
catch(Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
}
}
修改 完整的源代码如下：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace NOLANPAY
{
public partial class SalesUserEnd : Form
{
decimal SumValue = 0;
string invoiceNumber = generateInvoiceNumber();
int updateVolume;
string constring = ConfigurationManager.ConnectionStrings["MyDBConnectionString"].ToString();
public SalesUserEnd()
{
InitializeComponent();
}
private void Button2_Click(object sender, EventArgs e)
{
using (SqlConnection con = new SqlConnection(constring))
{
con.Open();
string query = "select * from productsmarket_Table where productname like '"+product_search.Text+"%' ";
using (SqlDataAdapter da = new SqlDataAdapter(query, con))
{
try
{
DataTable dt = new DataTable();
da.Fill(dt);
dataGridView1.DataSource = dt;
con.Close();
}
catch(Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
}
}
private void DataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
if (dataGridView1.SelectedRows.Count > 0)
{
string productName = dataGridView1.SelectedRows[0].Cells[1].Value + string.Empty;
string price = dataGridView1.SelectedRows[0].Cells[3].Value + string.Empty;
chprodName.Text = productName;
price_2.Text = price;
}
}
private void Button1_Click(object sender, EventArgs e)
{
CheckForInStockGoods();
decimal netPrice = Convert.ToDecimal(prod_qty.Text) * Convert.ToDecimal(price_2.Text);
string finalPrice = Convert.ToString(netPrice);
string DateOfPurchase = System.DateTime.Now.ToString();
string notify = "These items would be added to Tray, Please confirm?";
DialogResult result = MessageBox.Show(notify, "Confirm", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
if (result == DialogResult.Yes)
{
listView1.View = View.Details;
ListViewItem lvItem = listView1.Items.Add(chprodName.Text);
lvItem.SubItems.Add(price_2.Text);
lvItem.SubItems.Add(prod_qty.Text);
lvItem.SubItems.Add(finalPrice);
lvItem.SubItems.Add(DateOfPurchase);
}
}
private void CheckForInStockGoods()
{
using (SqlConnection con = new SqlConnection(constring))
{
con.Open();
string checkQuery = "select * from productsmarket_Table where productname like '" + product_search.Text + "%' ";
using (SqlCommand cmd = new SqlCommand(checkQuery, con))
{
try
{
using (SqlDataReader rd = cmd.ExecuteReader())
{
if (rd.Read())
{
int availableQty = Convert.ToInt32((rd["productQty"].ToString()));
if (availableQty == 0)
{
MessageBox.Show("You cannot Place This Order\n You appear to be out of stock!", "Out of Stock", MessageBoxButtons.OK, MessageBoxIcon.Error);
return;
}
}
}
}
catch(Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
}
}
private void Button5_Click(object sender, EventArgs e)
{
}
public static string generateInvoiceNumber()
{
string shopMasterPrologue = "#SHOPMAS1";
Random rand = new Random();
int randomLength = rand.Next(1, 6900);
string FinalRandom = shopMasterPrologue + randomLength;
return FinalRandom;
}
private void Button3_Click(object sender, EventArgs e)
{
decimal finalPrice = Convert.ToDecimal(excess.Text) - Convert.ToDecimal(totalPrice.Text);
//decimal FinalBalance = Convert.ToDecimal(finalPrice); // Aww Snap, i dont need this sir!
bal.Text = Convert.ToString(finalPrice);
button3.Enabled = false;
button3.Text = "Balance Calculated";
string changeInfo = "Recieved by Sammi" + " For The Products: " + getAllboughtProds() + "With Excess Balace of : "+bal.Text + " And Excess Payment of "+ excess.Text + " On " + System.DateTime.Now;
SaveTransactionRecord(invoiceNumber, changeInfo);
}
private void SalesUserEnd_Load(object sender, EventArgs e)
{
label9.Text = " ";
}
private void Button5_Click_1(object sender, EventArgs e)
{
foreach (ListViewItem lstItem in listView1.Items)
{
SumValue += decimal.Parse(lstItem.SubItems[3].Text);
label9.Text = "Total : NGN "+ SumValue;
totalPrice.Text = Convert.ToString(SumValue);
button5.Enabled = false;
button5.Text = "Calculated";
excess.Text = "0.00";
bal.Text = "0.00";
}
DialogResult res = MessageBox.Show("Price as at checkout is : " + SumValue + " Please Select Yes to Confirm Order", "Confirm", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
if (res == DialogResult.Yes)
{
string info = "Recieved by Sammi" + " For The Products: "+ getAllboughtProds() + " On "+System.DateTime.Now;
MessageBox.Show("Order Complete!");
//Save for Transaction and generate
UpdateProductQuantity();
SaveTransactionRecord(invoiceNumber,info);
}
}
private void UpdateProductQuantity()
{
using (SqlConnection con = new SqlConnection(constring))
{
con.Open();
//Starting calls.
//Select all first to check for Quantity
string updateQtyQuery = "select* from productsmarket_Table where productname like '"+product_search.Text+"%' ";
using (SqlCommand cmd = new SqlCommand(updateQtyQuery, con))
{
using (SqlDataReader rd = cmd.ExecuteReader())
{
if (rd.Read())
{
int orginalQty = Convert.ToInt32((rd["productQty"].ToString()));
updateVolume = orginalQty - Convert.ToInt32(prod_qty.Text);
}
}
string updateSqlQuantity = "update productsmarket_Table set productQty = @productQty where productname= @productname";
using (SqlCommand cmd2 = new SqlCommand(updateSqlQuantity, con))
{
try
{
cmd2.Parameters.AddWithValue("@productQty", updateVolume);
cmd2.Parameters.AddWithValue("@productname", product_search.Text);
cmd2.ExecuteNonQuery();
//Works Good!
}
catch(Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
}
}
}
private void SaveTransactionRecord(string invoiceNumber,string data)
{
using (SqlConnection con = new SqlConnection(constring))
{
con.Open();
string saveQuery = "insert into salesTransactionTable (invoiceNumber,data,transactionDate) values (@invoiceNumber,@data,@transactionDate)";
using (SqlCommand cmd = new SqlCommand(saveQuery,con))
{
try
{
cmd.Parameters.AddWithValue("@invoiceNumber",invoiceNumber);
cmd.Parameters.AddWithValue("@data", data);
cmd.Parameters.AddWithValue("@transactionDate", System.DateTime.Now);
cmd.ExecuteNonQuery();
}
catch(Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
}
}
private string getAllboughtProds()
{
string allBoughtItems = null;
foreach (ListViewItem lstItem in listView1.Items)
{
allBoughtItems += lstItem.SubItems[0].Text + ",";
}
return allBoughtItems;
}
private void Button4_Click(object sender, EventArgs e)
{
if (printPreviewDialog1.ShowDialog() == DialogResult.OK)
{
printDocument1.Print();
}
}
private void PrintDocument1_PrintPage(object sender, System.Drawing.Printing.PrintPageEventArgs e)
{
int x = 100, y = 100;
/*Image newImage = Properties.Resources.logo;
int width = 150, height = 70;
int ix = x, iy = y; //image position
e.Graphics.DrawImage(newImage, ix, iy, width, height);*/
var header = new Font("Calibri", 21, FontStyle.Bold);
int hdy = (int)header.GetHeight(e.Graphics); //30; //line height spacing
var fnt = new Font("Courier New", 10, FontStyle.Bold);
int dy = (int)fnt.GetHeight(e.Graphics); //20; //line height spacing
e.Graphics.DrawString("Receipt", header, Brushes.Black, new PointF(x, y)); y += hdy;
e.Graphics.DrawString("Invoice #: " + invoiceNumber, fnt, Brushes.Black, new PointF(x, y)); y += dy;
e.Graphics.DrawString("-----------------------------------------------------------", fnt, Brushes.Black, new PointF(x, y)); y += dy;
e.Graphics.DrawString(" Product Name "+" | "+" Price " + " | "+" Qty" +" | "+ " Net Price " , fnt, Brushes.Black, new PointF(x, y)); y += dy;
e.Graphics.DrawString("-----------------------------------------------------------", fnt, Brushes.Black, new PointF(x, y)); y += dy;
for (int i = 0; i < listView1.Items.Count; i++)
{
// Draw the row details for ? receipt
e.Graphics.DrawString(" " + listView1.Items[i].SubItems[0].Text +" | " + listView1.Items[i].SubItems[1].Text +" | "+
listView1.Items[i].SubItems[2].Text + " | "+ listView1.Items[i].SubItems[3].Text, fnt, Brushes.Black, new PointF(x, y)); y += dy;
}
e.Graphics.DrawString("---------------------", fnt, Brushes.Black, new PointF(x, y)); y += dy;
e.Graphics.DrawString("Total : " + totalPrice.Text, fnt, Brushes.Black, new PointF(x, y)); y += dy;
e.Graphics.DrawString("Excess : " + excess.Text, fnt, Brushes.Black, new PointF(x, y)); y += dy;
e.Graphics.DrawString("Balance : " + bal.Text, fnt, Brushes.Black, new PointF(x, y)); y += dy;
e.Graphics.DrawString("------------------------------------------------------", fnt, Brushes.Black, new PointF(x, y)); y += dy;
e.Graphics.DrawString("Thank you for your Patronage ", fnt, Brushes.Black, new PointF(x, y)); y += dy;
}
}
}
答案 0 :(得分：2)
您应该考虑将CheckForInStockGoods方法的返回类型修改为bool，如果false而不是简单地availableQty == 0，则返回return。在通常情况下，返回true。
然后更改Button1_Click方法中的逻辑。做这样的事情：
if(CheckForInStockGoods())
{
// your usual piece of logic to run if the goods are in stock.
}
答案 1 :(得分：1)
通过return语句，您可以退出方法/函数，从而退出范围。
很抱歉，以后的编辑/添加。
只有在离开返回值的方法或提早离开方法时，才必须使用return语句。
我给你举个例子：
public void Foo() {
// No return value
if (myCondition == expectedValue) {
// Do something with data
} else {
// myCondition has an unexpected value; ABORT
return; // Leave early
}
// Do more stuff (this could also be shortened)
}
public int Bar() {
if (myCondition == badValue) {
return myErrorCode; // We're exiting the method early with an error code
// You could also do this w/ exceptions
}
// No need for else
DoStuffWData(myData);
// Some condition where the data is returned, and not zero
if (myData == ushort.MaxValue) {
return myData;
}
return 0; // Mandatory return; the method returns a value.
}