NSMutableString replace 字串置換

NSMutableString replace 字串置換方法

!!!Range定義
 typedef struct _NSRange {
    NSUInteger location;
    NSUInteger length;
} NSRange;
location其實就是index
length表示從index開始幾個字元
...

    NSMutableString *myMSstr1;
    NSMutableString *myMSstr2;
    myMSstr1 = [NSMutableString stringWithFormat: @"Please don't see."];
    // replace a range of chars with another (replace:置換)(將Range範圍內的字元替換)
    [myMSstr1 replaceCharactersInRange: NSMakeRange(7, 10)
                        withString: @"see me."];
    NSLog(@"%@", myMSstr1);
        
    myMSstr2 = [NSMutableString stringWithFormat: @"%@%@%@%@%@", myMSstr1, myMSstr1, myMSstr1, myMSstr1, myMSstr1];
        
    NSString            *search, *replace;
    NSRange RangeOfStr;
    // Search and replace
    search = @"see me.";
    replace = @"don't see.";
    RangeOfStr = [myMSstr1 rangeOfString: search];
    if(RangeOfStr.location != NSNotFound){
        [myMSstr1 replaceCharactersInRange: RangeOfStr withString: replace];
        NSLog(@"%@", myMSstr1);
    }
    // Search and replace All  搜尋所有search字串置換為replace字串
    RangeOfStr = [myMSstr2 rangeOfString: search];
    while(RangeOfStr.location != NSNotFound){
        [myMSstr2 replaceCharactersInRange: RangeOfStr withString: replace];
        NSLog(@"%@", myMSstr2);
        RangeOfStr = [myMSstr2 rangeOfString: search];
    }
執行結果：

NSNumber::比較大小

NSNumber compare

!!! 切記！儲存於NSNumber物件的值，擷取時必須要一致。
擷取時輸出型態與儲存時的型態不同時，系統並不會出錯，而會輸出無效的值

        NSNumber        *myNumber, *floatNumber, *intNumber;
        NSInteger       myInt;
        NSComparisonResult compareResult1, compareResult2;

        intNumber = [NSNumber numberWithInteger: 100];
        floatNumber = [NSNumber numberWithFloat: 100.00];
        myNumber = [NSNumber numberWithDouble: 123456e+15];
        
        compareResult1 = [intNumber compare: myNumber];
        compareResult2 = [intNumber compare: floatNumber];
        //NSOrderedAscending    <  官方解釋(The left operand is smaller than the right operand.)
        //NSOrderedSame        ==  官方解釋(The two operands are equal.)
        //NSOrderedDescending   >  官方解釋(The left operand is greater than the right operand.)
        if(compareResult1 == NSOrderedAscending)
            NSLog(@"intNumber is less than myNumber");
        else if(compareResult1 == NSOrderedSame)
            NSLog(@"intNumber is equal to myNumber");
        else if(compareResult1 == NSOrderedDescending)
            NSLog(@"intNumber is greater than myNumber");
        else
            NSLog(@"What the fuck?!");

        if(compareResult1 == NSOrderedAscending)
            NSLog(@"intNumber is less than floatNumber");
        else if(compareResult1 == NSOrderedSame)
            NSLog(@"intNumber is equal to floatNumber");
        else if(compareResult1 == NSOrderedDescending)
            NSLog(@"intNumber is greater than floatNumber");
        else
            NSLog(@"What the fuck?!");

執行結果：

NSString::取得字串長度(Get NSString Length)  

NSString *str1 = @"This is string A";
NSLog(@"Length of str1: %lu", [str1 length]);

執行結果：

C# 已知空間三點，求圓心座標

C#

…

C# 已知空間三點，求圓心座標

public class PT
{
    public double x { get; set; }
    public double y { get; set; }
    public double z { get; set; }
};

PT FindCenterPoint(PT pd, PT pd2, PT pd3)
{
    double a1, b1, c1, d1;
    double a2, b2, c2, d2;
    double a3, b3, c3, d3;

    PT pd_center = new PT();
    a1 = (pd.y * pd2.z - pd2.y * pd.z - pd.y * pd3.z + pd3.y * pd.z + pd2.y * pd3.z - pd3.y * pd2.z);
    b1 = -(pd.x * pd2.z - pd2.x * pd.z - pd.x * pd3.z + pd3.x * pd.z + pd2.x * pd3.z - pd3.x * pd2.z);
    c1 = (pd.x * pd2.y - pd2.x * pd.y - pd.x * pd3.y + pd3.x * pd.y + pd2.x * pd3.y - pd3.x * pd2.y);
    d1 = -(pd.x * pd2.y * pd3.z - pd.x * pd3.y * pd2.z - pd2.x * pd.y * pd3.z + pd2.x * pd3.y * pd.z
         + pd3.x * pd.y * pd2.z - pd3.x * pd2.y * pd.z);

    a2 = 2 * (pd2.x - pd.x);
    b2 = 2 * (pd2.y - pd.y);
    c2 = 2 * (pd2.z - pd.z);
    d2 = pd.x * pd.x + pd.y * pd.y + pd.z * pd.z - pd2.x * pd2.x - pd2.y * pd2.y - pd2.z * pd2.z;

    a3 = 2 * (pd3.x - pd.x);
    b3 = 2 * (pd3.y - pd.y);
    c3 = 2 * (pd3.z - pd.z);
    d3 = pd.x * pd.x + pd.y * pd.y + pd.z * pd.z - pd3.x * pd3.x - pd3.y * pd3.y - pd3.z * pd3.z;

    pd_center.y = (a1 * c2 * d3 - a1 * c3 * d2 - a2 * c1 * d3 + a2 * c3 * d1 + a3 * c1 * d2 - a3 * c2 * d1)
        / (a1 * b2 * c3 - a1 * b3 * c2 - a2 * b1 * c3 + a2 * b3 * c1 + a3 * b1 * c2 - a3 * b2 * c1);
    pd_center.z = -(a1 * b2 * d3 - a1 * b3 * d2 - a2 * b1 * d3 + a2 * b3 * d1 + a3 * b1 * d2 - a3 * b2 * d1)
        / (a1 * b2 * c3 - a1 * b3 * c2 - a2 * b1 * c3 + a2 * b3 * c1 + a3 * b1 * c2 - a3 * b2 * c1);
    pd_center.x = -(b1 * c2 * d3 - b1 * c3 * d2 - b2 * c1 * d3 + b2 * c3 * d1 + b3 * c1 * d2 - b3 * c2 * d1)
        / (a1 * b2 * c3 - a1 * b3 * c2 - a2 * b1 * c3 + a2 * b3 * c1 + a3 * b1 * c2 - a3 * b2 * c1);
    return pd_center;
}

Objective Static

…

靜態變數預設的初始值為0，且執行期間只會被初始一次，以下使用Static關鍵字實現方法呼叫次數

@interface Page: NSObject
-(void) showTimes;
@end

@implementation Page
-(void) showTimes
{
    static int PageTimes;
    ++PageTimes;
    NSLog(@"showTimes Call Times : %i", PageTimes);
}
@end

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        
        Page *myPage = [Page new];
        [myPage showTimes];
        
        Page *myPage2 = [Page new];
        [myPage2 showTimes];
        
        Page *myPage3 = [Page new];
        [myPage3 showTimes];
        
    }
    return 0;
}

Linux硬碟裝置的認定

Linux硬碟裝置認定

1. ＩＤＥ裝置：
       以 hd 作為開頭，英文a、b、c、d排序。在傳統的主機板上，通常有兩個IDE排線插孔，每個排線可插兩顆硬碟或光碟。第一個IDE排線上的第一個裝置為/dev/hda，第二個裝置為/dev/hdb；第二個IDE排線上的第一個裝置為/dev/hdc，第二個裝置為/dev/hdd。
       分割硬碟依數字命名，/dev/hda1、/dev/hda2、/dev/hda3。
2. ＳＣＳＩ、ＳＡＴＡ與ＵＳＢ裝置：
       以 sd 作為開頭，英文a、b、c、d排序。第一個裝置為/dev/sda，第二個裝置為/dev/sdb，第三個裝置為/dev/sdc⋯⋯ 。
       分割硬碟依數字命名，/dev/sda1、/dev/sda2、/dev/sda3。