コード ```using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Windows.Forms; namespace GradeCheck { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { labelResultM.Text = "ちゃんだい"; labelResultP.Text = "たくちゃん"; labelResultE.Text = "しんちゃん"; labelCompAvgM.Text = "和樹"; labelCompAvgP.Text = "さっきーなぁ"; labelCompAvgE.Text = "組長"; } private void textBoxAttendanceM_TextChanged(object sender, EventArgs e) { } private void textBoxAttenDanceP_TextChanged(object sender, EventArgs e) { } private void textBoxScoreM_TextChanged(object sender, EventArgs e) { } private void buttonJudge_Click(object sender, EventArgs e) { //出席率を浮動小数点値に変換 double AttendanceM, AttendanceP, AttendanceE; textToValue(textBoxAttendanceM.Text, out AttendanceM); textToValue(textBoxAttendanceP.Text, out AttendanceP); textToValue(textBoxAttendanceE.Text, out AttendanceE); //点数を整数値に変換 int scoreM, scoreP, scoreE; textToValue(textBoxScoreM.Text, out scoreM); textToValue(textBoxScoreP.Text, out scoreP); textToValue(textBoxScoreE.Text, out scoreE); //点数を判定する labelResultM.Text = scoreJudge(AttendanceM, scoreM); labelResultP.Text = scoreJudge(AttendanceP, scoreP); labelResultE.Text = scoreJudge(AttendanceE, scoreE); //平均値以上か未満か判定する labelCompAvgM.Text = averageJudge(scoreM, 1); labelCompAvgP.Text = averageJudge(scoreP, 2); labelCompAvgE.Text = averageJudge(scoreE, 3); } //テキストを浮動小数点値に変換 //(仮引数) text : 変換する文字列 val : 変換した浮動小数点値 //(返却値) なし private void textToValue(String text, out double val) { if (double.TryParse(text, out val) == false) val = -1.0; } //テキストを整数値に変換 //(仮引数)text : 変換する文字列 val : 変換した整数値 //(返却値)なし private void textToValue(string text, out int val) { if (int.TryParse(text, out val) == false) val = -1; } //成績判定 //(仮引数) Attendance : 出席率 score : 得点 //(返却値) 判定結果 private string scoreJudge(double Attendance, int score) { string result; if (Attendance < 0.0 || Attendance > 100.0 || score < 0 || score > 100) result = "エラー"; else if (Attendance >= 20) { if (score >= 80) result = "アスペ"; else if (score >= 70) result = "基地外"; else if (score >= 60) result = "4級"; else result = "退席"; } else result = "退席"; return result; } //平均点判定 //(仮引数) score : 得点 subject : 科目 (1=数学 2=物理 3=英語) //(返却値) 判定結果 private string averageJudge(int score, int subject) { string result; int average; if (score < 0 || score > 100) return "エラー"; switch (subject) { case 1: average = 30; break; case 2: average = 60; break; case 3: average = 75; break; default: return "エラー"; } if (score >= average) result = "万歳"; else result = "天皇万歳"; return result; } private void buttonReset_Click(object sender, EventArgs e) { textBoxAttendanceM.Text = "0.0"; textBoxAttendanceP.Text = "0.0"; textBoxAttendanceE.Text = "0.0"; textBoxScoreM.Text = "0"; textBoxScoreP.Text = "0"; textBoxScoreE.Text = "0"; labelResultM.Text = ""; labelResultP.Text = ""; labelResultE.Text = ""; labelCompAvgM.Text = ""; labelCompAvgP.Text = ""; labelCompAvgE.Text = ""; } private void labelResultE_Click(object sender, EventArgs e) { } private void label7_Click(object sender, EventArgs e) { } private void label8_Click(object sender, EventArgs e) { } private void label6_Click(object sender, EventArgs e) { } private void textBoxAttendanceE_TextChanged(object sender, EventArgs e) { } private void textBoxScoreE_TextChanged(object sender, EventArgs e) { } private void textBoxScoreP_TextChanged(object sender, EventArgs e) { } private void button1_Click(object sender, EventArgs e) //② { } } } なぜ val = -1.0;やval = -1;を書くのかわからないのですが・・・・