Abnerの技术小栈
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Objective-C基础入门（决策）

发表于 分类于

if 语句

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int main (int argc, char * argv[]) { 
    @autoreleasepool {      
        int number;
        NSLog (@"Type in your number: ");    
        scanf ("%i", &number);
        if ( number < 0 )     
            number = -number;
        NSLog (@"The absolute value is %i", number);  
    }    
    return 0;
}

switch 语句

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int main (int argc, char * argv[]) {   
    @autoreleasepool {      
        double  value1, value2;    
        char    operator;    
        Calculator *deskCalc = [[Calculator alloc] init];
        
        NSLog (@"Type in your expression.");   
        scanf ("%lf %c %lf", &value1, &operator, &value2);
        [deskCalc setAccumulator: value1];
        
        switch ( operator ) {        
            case '+':            
                [deskCalc add: value2];    
                break;        
            case '-':       
                [deskCalc subtract: value2];     
                break;      
            case '*':        
                [deskCalc multiply: value2];       
                break;     
            case '/':          
                [deskCalc divide: value2];      
                break;    
            default:       
                NSLog (@"Unknown operator.");    
                break;       
        }
        NSLog (@"%.2f", [deskCalc accumulator]);  
    }
    return 0; 
}

Boolean变量

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int main (int argc, char * argv[]) {   
    @autoreleasepool {    
        int   p, d, isPrime;

        for ( p = 2; p <= 50; ++p ) {       
            isPrime = 1;
            for ( d = 2; d < p; ++d )         
                if ( p % d == 0 )         
                    isPrime = 0;
            if ( isPrime != 0 )      
                NSLog (@"%i ", p);    
        }  
    }
    return 0; 
}

条件操作符

condition ? expression1 : expression2

特殊扩展
condition ?: expression
如果condition是true，那么value是condition
如果condition是false，那么value是expression