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tutorial:conditionalstatement [2019/01/03 12:29] admin [If - Statements] |
tutorial:conditionalstatement [2019/01/07 13:00] admin [Break, Continue, Exit and Goto] |
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^ Statements ^ Syntax ^ | ^ Statements ^ Syntax ^ | ||
|If..Then|<sxh delphi;> | |If..Then|<sxh delphi;> | ||
- | //---Single Statement--- | ||
if {Condition} then {Statement}; | if {Condition} then {Statement}; | ||
+ | </sxh> | | ||
+ | |If..Then..Else|<sxh delphi;> | ||
+ | if {Condition} then | ||
+ | {Statement1} | ||
+ | else | ||
+ | {Statement2}; | ||
+ | </sxh> | | ||
+ | |If..Then/ Else If..Then/ Else|<sxh delphi;> | ||
+ | if {Condition1} then | ||
+ | {Statement1} | ||
+ | else if {Condition2} then | ||
+ | {Statement2} | ||
+ | else | ||
+ | {Statement3}; | ||
+ | </sxh> | | ||
+ | |||
+ | จากตารางข้างบน เป็นรูปแบบ If ที่มี statement แค่บรรทัดเดียวต่อหนึ่ง condition เท่านั้น อย่างไรก็ตามหากมี statement หลายบรรทัด ต้องเติม begin .. end ด้วยทุกครั้ง ดังนี้ | ||
- | //---Multiple Statements--- | + | <hidden If-Statement: Multiple Statements> |
+ | |If..Then|<sxh delphi;> | ||
if {Condition} then | if {Condition} then | ||
begin | begin | ||
Line 15: | Line 32: | ||
</sxh> | | </sxh> | | ||
|If..Then..Else|<sxh delphi;> | |If..Then..Else|<sxh delphi;> | ||
- | //---Single Statement--- | ||
- | if {Condition} then | ||
- | {Statement1} | ||
- | else | ||
- | {Statement2}; | ||
- | |||
- | //---Multiple Statements--- | ||
if {Condition} then | if {Condition} then | ||
begin | begin | ||
Line 35: | Line 45: | ||
end; | end; | ||
</sxh> | | </sxh> | | ||
- | \\ | + | |If..Then/ Else If..Then/ Else|<sxh delphi;> |
- | <hidden Example-1: If Statements (If..Else If..Else)> | + | //---Single Statement--- |
- | **ตัวอย่าง** โปรแกรมตัดคะแนน ให้กลายเป็นเกรด A-F\\ | + | if {Condition1} then |
- | <sxh delphi;highlight: [9-21]> | + | begin |
- | program Nested_If_Then_Else; | + | {Statement1}; |
+ | {Statement2}; | ||
+ | {...}; | ||
+ | end | ||
+ | else if {Condition2} then | ||
+ | begin | ||
+ | {Statement3}; | ||
+ | {Statement4}; | ||
+ | {...}; | ||
+ | end | ||
+ | else | ||
+ | begin | ||
+ | {Statement5}; | ||
+ | {Statement6}; | ||
+ | {...}; | ||
+ | end; | ||
- | var Score:real; | + | </sxh> | |
+ | </hidden> \\ | ||
- | begin | ||
- | write('Please insert your score(0-100): '); | ||
- | readln(Score); | ||
- | if (Score<50)and(Score>0) then | ||
- | writeln('Your Grade is : F') | ||
- | else if Score<60 then | ||
- | writeln('Your Grade is : D') | ||
- | else if Score<70 then | ||
- | writeln('Your Grade is : C') | ||
- | else if Score<80 then | ||
- | writeln('Your Grade is : B') | ||
- | else if Score<80 then | ||
- | writeln('Excellent!, your gade is : A') | ||
- | else | ||
- | writeln('Your score is not correct!'); | ||
- | |||
- | readln(); | ||
- | end. | ||
- | </sxh> | ||
- | | ||
- | </hidden> | ||
- | |||
- | <hidden Example-2: If Statements (Nested If)> | ||
- | **ตัวอย่าง** โปรแกรมตัดคะแนน ให้กลายเป็นเกรด A-F\\ | ||
- | __**ข้อสังเกต**__ มีการใช้ If ซ้อน If (Nested If) | ||
- | นอกจากนี้ให้ลองสังเกต If..Then..Else if..Else ในบรรทัดที่ 12-21 | ||
- | จะเห็นว่าไม่มีการใช้ Begin ... End | ||
- | เพราะถือเป็น Blog เดียวกัน\\ | ||
- | <sxh delphi;highlight: [9-21]> | ||
- | program Nested_If_Then_Else; | ||
- | |||
- | var Score:real; | ||
- | |||
- | begin | ||
- | write('Please insert your score(0-100): '); | ||
- | readln(Score); | ||
- | if (Score<0)or(Score>100) then | ||
- | writeln('Your score is not correct!!') | ||
- | else | ||
- | if Score<50 then | ||
- | writeln('Your Grade is : F') | ||
- | else if Score<60 then | ||
- | writeln('Your Grade is : D') | ||
- | else if Score<70 then | ||
- | writeln('Your Grade is : C') | ||
- | else if Score<80 then | ||
- | writeln('Your Grade is : B') | ||
- | else | ||
- | writeln('Excellent!, your Grade is : A'); | ||
- | readln(); | ||
- | end. | ||
- | </sxh> | ||
- | | ||
- | </hidden> \\ \\ | ||
===== Case - Statements ===== | ===== Case - Statements ===== | ||
Line 109: | Line 81: | ||
2: {Statement2}; | 2: {Statement2}; | ||
3: {Statement3}; | 3: {Statement3}; | ||
+ | else {Statement4}; | ||
+ | end; | ||
+ | </sxh> | | ||
+ | |Range|<sxh delphi;> | ||
+ | case {Var} of | ||
+ | 1..10: {Statement1}; | ||
+ | 11..20: {Statement2}; | ||
+ | 21..30: {Statement3}; | ||
else {Statement4}; | else {Statement4}; | ||
end; | end; | ||
- | //---Multiple Statements--- | + | </sxh> | |
+ | |||
+ | จากตารางข้างบน เป็นรูปแบบ Case ที่มี statement แค่บรรทัดเดียวต่อหนึ่ง condition เท่านั้น อย่างไรก็ตามหากมี statement หลายบรรทัด ต้องเติม begin .. end ด้วยทุกครั้ง ดังนี้ | ||
+ | |||
+ | |||
+ | <hidden Case-Statements: Multiple Statements> | ||
+ | ^ Statements ^ Syntax ^ | ||
+ | |Exact value|<sxh delphi;> | ||
case {Var} of | case {Var} of | ||
1: begin | 1: begin | ||
Line 130: | Line 117: | ||
</sxh> | | </sxh> | | ||
|Range|<sxh delphi;> | |Range|<sxh delphi;> | ||
- | //---Single Statement--- | ||
case {Var} of | case {Var} of | ||
- | 1..10: {Statement1}; | + | 1..10: begin |
- | 11..20: {Statement2}; | + | {Statement1}; |
- | 21..30: {Statement3}; | + | {Statement2}; |
- | else {Statement4}; | + | ...; |
+ | end; | ||
+ | 11..20: begin | ||
+ | {Statement3}; | ||
+ | {Statement4}; | ||
+ | ...; | ||
+ | end; | ||
+ | 21..30: begin | ||
+ | {Statement5}; | ||
+ | {Statement6}; | ||
+ | ...; | ||
+ | end; | ||
+ | else begin | ||
+ | {Statement7}; | ||
+ | {Statement8}; | ||
+ | ...; | ||
+ | end; | ||
end; | end; | ||
</sxh> | | </sxh> | | ||
- | \\ | + | </hidden> \\ |
- | <hidden Example-3: Case Statements> | + | ===== Break, Continue, Exit and Goto ===== |
- | **ตัวอย่าง** โปรแกรมตัดคะแนน ให้กลายเป็นเกรด A-F\\ | + | คำสั่ง Break, Continue, Exit และ Goto สรุปได้ดังนี้ |
- | <sxh delphi;highlight: [10-16]> | + | |
- | program TestCaseStatement; | + | |
- | var score:integer; | + | ^ Procedures ^ Meaning ^ Format ^ |
- | Grade:char; | + | | Break | ออกจาก Loop ปัจจุบัน (For/While/Repeat) |<sxh delphi;> |
+ | for i:=1 to 10 do | ||
+ | if i=5 then break; | ||
+ | writeln('i = ',i); //i = 5 | ||
+ | readln; | ||
+ | </sxh> | | ||
+ | |Continue| สิ้นสุด Loop ปัจจุบันทันที เพื่อเริ่ม Loop ปัจจุบันใหม่ในรอบถัดไป (For/While/Repeat) |<sxh delphi;> | ||
+ | for i:=1 to 5 do | ||
+ | begin | ||
+ | if i=4 then continue; | ||
+ | writeln('i = ',i); //i = 4 won't be showed | ||
+ | end; | ||
+ | </sxh> | | ||
+ | |Exit| ออกจาก Sub-Program ปัจจุบัน (Procedure/Function) |<sxh delphi;> | ||
+ | procedure MyProc; | ||
begin | begin | ||
- | write('Insert your score (0 to 100): '); | + | exit; |
- | readln(score); | + | writeln('After Exit'); //This won't be shown |
- | + | end; | |
- | case score of | + | </sxh> | |
- | 0..50: Grade:='F'; | + | |Goto| ไปยัง Label ที่ระบุ |<sxh delphi;> |
- | 51..60: Grade:='D'; | + | label PointA,PointB; //declare labels |
- | 61..70: Grade:='C'; | + | BEGIN |
- | 71..80: Grade:='B'; | + | Goto PointB; |
- | else Grade:='A'; | + | PointA: |
- | end; | + | wrtieln('Passing PointA'); |
- | + | exit; //Exit the program | |
- | writeln('Your grade is: ',Grade); | + | PointB: |
- | readln(); | + | wrtieln('Passing PointB'); |
- | end. | + | Goto PointA; |
- | </sxh> | + | END. |
- | + | </sxh> | | |
- | Compiled Results: | + | |
- | + | ||
- | Insert your score (0 to 100): 35 | + | |
- | Your grade is: F | + | |
- | + | ||
- | </hidden> \\ \\ | + | |
- | + | ||
- | ===== Break, Continue and Goto ===== | + |