Csharp/C Sharp/Language Basics/If
Содержание
- 1 Another if else
- 2 Demonstrate a block of code
- 3 Demonstrate the if
- 4 Determine if a value is positive, negative, or zero
- 5 Determine if a value is positive or negative
- 6 If Branching
- 7 If Else
- 8 If else for int
- 9 illustrates the use of a nested if statement
- 10 Illustrates the use of an if statement that executes a block
- 11 Illustrates the use of the if statement
- 12 Logical operators with an if statement
Another if else
<source lang="csharp"> /* Learning C# by Jesse Liberty Publisher: O"Reilly ISBN: 0596003765
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using System; public class NestIfValues { static void Main() { int temp = 32; if (temp <= 32) { Console.WriteLine("Warning! Ice on road!"); if (temp == 32) { Console.WriteLine( "Temp exactly freezing, beware of water."); } else { Console.WriteLine("Watch for black ice! Temp: {0}", temp); } } } } </source>
Demonstrate a block of code
<source lang="csharp"> /* C#: The Complete Reference by Herbert Schildt Publisher: Osborne/McGraw-Hill (March 8, 2002) ISBN: 0072134852
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// Demonstrate a block of code.
using System;
public class BlockDemo {
public static void Main() { int i, j, d; i = 5; j = 10; // the target of this if is a block if(i != 0) { Console.WriteLine("i does not equal zero"); d = j / i; Console.WriteLine("j / i is " + d); } }
}
</source>
Demonstrate the if
<source lang="csharp"> /* C#: The Complete Reference by Herbert Schildt Publisher: Osborne/McGraw-Hill (March 8, 2002) ISBN: 0072134852
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// Demonstrate the if.
using System;
public class IfDemo {
public static void Main() { int a, b, c; a = 2; b = 3; if(a < b) Console.WriteLine("a is less than b"); // this won"t display anything if(a == b) Console.WriteLine("you won"t see this"); Console.WriteLine(); c = a - b; // c contains -1 Console.WriteLine("c contains -1"); if(c >= 0) Console.WriteLine("c is non-negative"); if(c < 0) Console.WriteLine("c is negative"); Console.WriteLine(); c = b - a; // c now contains 1 Console.WriteLine("c contains 1"); if(c >= 0) Console.WriteLine("c is non-negative"); if(c < 0) Console.WriteLine("c is negative"); }
}
</source>
Determine if a value is positive, negative, or zero
<source lang="csharp"> /* C#: The Complete Reference by Herbert Schildt Publisher: Osborne/McGraw-Hill (March 8, 2002) ISBN: 0072134852
- /
// Determine if a value is positive, negative, or zero. using System;
public class PosNegZero {
public static void Main() { int i; for(i=-5; i <= 5; i++) { Console.Write("Testing " + i + ": "); if(i < 0) Console.WriteLine("negative"); else if(i == 0) Console.WriteLine("no sign"); else Console.WriteLine("positive"); } }
}
</source>
Determine if a value is positive or negative
<source lang="csharp"> /* C#: The Complete Reference by Herbert Schildt Publisher: Osborne/McGraw-Hill (March 8, 2002) ISBN: 0072134852
- /
// Determine if a value is positive or negative. using System;
public class PosNeg {
public static void Main() { int i; for(i=-5; i <= 5; i++) { Console.Write("Testing " + i + ": "); if(i < 0) Console.WriteLine("negative"); else Console.WriteLine("positive"); } }
}
</source>
If Branching
<source lang="csharp"> /* Learning C# by Jesse Liberty Publisher: O"Reilly ISBN: 0596003765
- /
using System; namespace Branching { public class TestBranching { static void Main() { int valueOne = 10; int valueTwo = 20; int valueThree = 30; Console.WriteLine("Testing valueOne against valueTwo..."); if ( valueOne > valueTwo ) { Console.WriteLine( "ValueOne: {0} larger than ValueTwo: {1}", valueOne, valueTwo); } Console.WriteLine("Testing valueThree against valueTwo..."); if ( valueThree > valueTwo ) { Console.WriteLine( "ValueThree: {0} larger than ValueTwo: {1}", valueThree, valueTwo); } // end if } // end Main } // end class } // end namespace </source>
If Else
<source lang="csharp"> /* Learning C# by Jesse Liberty Publisher: O"Reilly ISBN: 0596003765
- /
using System; namespace Branching { public class TestIfElse { static void Main() { int valueOne = 10; int valueTwo = 20; Console.WriteLine("Testing valueOne against valueTwo..."); if ( valueOne > valueTwo ) { Console.WriteLine( "ValueOne: {0} larger than ValueTwo: {1}", valueOne, valueTwo); } // end if else { Console.WriteLine( "Nope, ValueOne: {0} is NOT larger than ValueTwo: {1}", valueOne, valueTwo); } // end else } // end Main } // end class } // end namespace </source>
If else for int
<source lang="csharp"> /*
* C# Programmers Pocket Consultant * Author: Gregory S. MacBeth * Email: gmacbeth@comporium.net * Create Date: June 27, 2003 * Last Modified Date: */
using System; namespace Client.Chapter_4___Program_Control {
public class ifelse { static void Main(string[] args) { int a = 5, b = 5, c = 10; if (a == b) Console.WriteLine(a); if ((a > c) || (a == b)) Console.WriteLine(b); if ((a >= c) && (b <= c)) Console.WriteLine(c); } }
}
</source>
illustrates the use of a nested if statement
<source lang="csharp"> /* Mastering Visual C# .NET by Jason Price, Mike Gunderloy Publisher: Sybex; ISBN: 0782129110
- /
/*
Example4_3.cs illustrates the use of a nested if statement
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public class Example4_3 {
public static void Main() { int reactorTemp = 1500; string emergencyValve = " "; if (reactorTemp < 1000) { System.Console.WriteLine("Reactor temperature normal"); } else { System.Console.WriteLine("Reactor temperature too high!"); if (emergencyValve == "closed") { System.Console.WriteLine("Reactor meltdown in progress!"); } } }
}
</source>
Illustrates the use of an if statement that executes a block
<source lang="csharp"> /* Mastering Visual C# .NET by Jason Price, Mike Gunderloy Publisher: Sybex; ISBN: 0782129110
- /
/*
Example4_2.cs illustrates the use of an if statement that executes a block
- /
public class Example4_2 {
public static void Main() { int smallNumber = 5; int bigNumber = 100; if (bigNumber < smallNumber) { System.Console.Write(bigNumber); System.Console.Write(" is less than "); System.Console.Write(smallNumber); } else { System.Console.Write(smallNumber); System.Console.Write(" is less than "); System.Console.Write(bigNumber); } }
}
</source>
Illustrates the use of the if statement
<source lang="csharp"> /* Mastering Visual C# .NET by Jason Price, Mike Gunderloy Publisher: Sybex; ISBN: 0782129110
- /
/*
Example4_1.cs illustrates the use of the if statement
- /
public class Example4_1 {
public static void Main() { int smallNumber = 5; int bigNumber = 100; if (bigNumber > smallNumber) System.Console.WriteLine(bigNumber + " is greater than " + smallNumber); else System.Console.WriteLine(bigNumber + " is less than " + smallNumber); }
}
</source>
Logical operators with an if statement
<source lang="csharp"> /* Mastering Visual C# .NET by Jason Price, Mike Gunderloy Publisher: Sybex; ISBN: 0782129110
- /
/*
Example4_4.cs illustrates the use of logical operators with an if statement
- /
public class Example4_4 {
public static void Main() { int reactorTemp = 1500; string emergencyValve = "closed"; if ((reactorTemp > 1000) && (emergencyValve == "closed")) { System.Console.WriteLine("Reactor meltdown in progress!"); } }
}
</source>