字符串作业题目以及答案1

1.现有如下定义的字符串： NSMutableString * str=@“iphoneAndroid”,能不能对该字符串进行修改，如果能，请输出删除Android后的新字符串。 2求字符串“158”和“39”按十进制数值做差后的结果以字符串形式输出 3取出符串“123-456-789-000”中的数字部分，组成一个新的字符串输出，（提示：可变字符串；返回数组） 4放四个十进制三位数到一个数组中，然后按从小到大排序后组成一个新的数组

答案：

#import "KAppDelegate.h"

@implementation KAppDelegate

- (void)dealloc

{

[_window release];

[super dealloc];

}

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions

{

self.window = [[[UIWindowalloc] initWithFrame:[[UIScreenmainScreen] bounds]] autorelease];

//1

NSMutableString *str = [[NSMutableStringalloc] initWithString:@"iphoneAndroid"];

NSRange r1 = {6,7};

NSRange r2 = NSMakeRange(6, 7);

[str deleteCharactersInRange:r2];

NSLog(@"str = %@",str);

[str release];

//2

int a = 158;

int b = 39;

int c = a - b;

NSString *str1 = [NSString stringWithFormat:@"%d",c];

NSLog(@"str1 = %@",str1);

//3

NSString *str2 = @"123-456-789-000";

NSArray *arr = [str2 componentsSeparatedByString:@"-"];

NSLog(@"arr = %@",arr);

NSString *str3=[arr componentsJoinedByString:@""];

NSLog(@"str3 = %@",str3);

//4

NSMutableArray *arr2 = [NSMutableArrayarrayWithObjects:@"901",@"675",@"110",@"123",nil];

//NSArray *ar = @[@"123",@"345"];／／只支持6.0以上的系统

for (int i = 0; i<arr2.count - 1; i++)

{

for (int j = 0; j < arr2.count - i - 1; j++)

{

NSString *p = [arr2 objectAtIndex:j];

NSString *q = [arr2 objectAtIndex:j+1];

if ([p intValue] > [q intValue])

{

//[arr2 exchangeObjectAtIndex:j+1 withObjectAtIndex:j];//只支持6.0以上的系统

NSString *tmp = arr2[j];

arr2[j] = arr2[j+1];

arr2[j+1] = tmp;

}

}

}

NSLog(@"arr2 = %@",arr2);

self.window.backgroundColor = [UIColorwhiteColor];

[self.windowmakeKeyAndVisible];

returnYES;

}