鍍金池/ 教程/ C/ Objective-C if語句
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Objective-C if語句

if語句由一個布爾表達式后跟一個或多個語句。

語法:

在Objective-C編程語言的if語句的語法是:

if(boolean_expression)
{
   /* statement(s) will execute if the boolean expression is true */
}

如果布爾表達式的計算結(jié)果為true,那么里面的代碼塊,如果語句會被執(zhí)行。如果布爾表達式計算為false,那么結(jié)束后的第一套代碼的if語句(后右大括號)將被執(zhí)行。

Objective-C語言的編程語言假設(shè)為true,任何非零和非空值,如果它是零或者為null,那么它被假定為false。

流程圖:

Objective-C if statement

例如:

#import <Foundation/Foundation.h>
 
int main ()
{
   /* local variable definition */
   int a = 10;
 
   /* check the boolean condition using if statement */
   if( a < 20 )
   {
       /* if condition is true then print the following */
       NSLog(@"a is less than 20
" );
   }
   NSLog(@"value of a is : %d
", a);
 
   return 0;
}

上面的代碼編譯和執(zhí)行時,它會產(chǎn)生以下結(jié)果:

2013-09-07 22:07:00.845 demo[13573] a is less than 20
2013-09-07 22:07:00.845 demo[13573] value of a is : 10

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