关于OC常用字符串函数介绍

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关于OC常用字符串函数介绍

1.格式化字符串：stringWithFormat

//1 定义一个字符串NSString * s = @"My age is";//2 定义一个整形变量int myAge = 18;//3 将字符串s 和 整形变量myAge 组合成一个字符串NSString * s2 = [NSString stringWithFormat:@"%@%d",s,myAge];//4 输出打印NSLog(@"%@",s2);

2.C语言的字符串转化： stringWithUTF8String

//1 定义一个c语言字符串char *s = "我是c语言字符串";//2 将其转化为oc的字符串NSString *str = [NSString stringWithUTF8String:s];//3 输出打印NSLog(@"str -- %@",str);

3.将字符串中大写字母变成小写：lowercaseString

//1 定义一个字符串NSString * s = @"THIS MY STRING";//2 用lowercaseString转化NSString * str =[s lowercaseString];//3 输出打印NSLog(@"str -- %@",str);

4.将字符串中小写字母变成大写：uppercaseString

//1 定义一个字符串NSString * s = @"this my string";//2 用uppercaseString转化NSString * str =[s uppercaseString];//3 输出打印NSLog(@"str -- %@",str);

5.将字符串中单词的首字母大写：capitalizedString

//1 定义一个字符串NSString * s = @"this my string";//2 用capitalizedString转化NSString * str = [s capitalizedString];//3 输出打印NSLog(@"str -- %@",str);

6.比较字符串是否相同：有 isEqualToString 和 compare

//1 定义两个字符串NSString * s1 = @"this my string";NSString * s2 = @"that my string";//2 首先用isEqualToString比较if([s1 isEqualToString:s2]){ NSLog(@"他们是相同的");}else{ NSLog(@"他们是不同的");}//3 用compare比较int cmp = [s1 compare:s2];if(cmp==0){ NSLog(@"他们是相同的");}else if(cmp==1){ NSLog(@"s1是大于s2的");}else if(cmp==-1){ NSLog(@"s1是小于s2的");}

7.检查前缀：hasPrefix 和检查后缀：hasSuffix

//1 定义一个字符串NSString * s = @"http://my.oschina.net/purpleDog";//2 用hasPrefix检查前缀是否为httpif([s hasPrefix:@"http"]){ NSLog(@"前缀是http");}else{ NSLog(@"前缀不是http");}//3 用hasSuffix检查后缀是否是purpleDogif([s hasSuffix:@"purpleDog"]){ NSLog(@"后缀是purpleDog");}else{ NSLog(@"后缀不是purpleDog");}

8.字符串截取：substringWithRange

//1 定义一个字符串NSString * s = @"0123456789";//2 截取1-3    NSMakeRange(1,3)  1代表从哪个字符开始截取，3代表截取长度;    NSString * str = [s substringWithRange:NSMakeRange(1,3)];//3 输出打印NSLog(@"str -- %@",str);

9.获取字符串中的字母：characterAtIndex

//1 定义一个字符串NSString *s = @"purpleDog";    //2 循环输出字符    for (int i = 0; i < s.length; i++) {  NSLog(@"%c",[s characterAtIndex:i]);}

10.替换字符串中的一段：stringByReplacingOccurrencesOfString

//1 定义一个字符串   NSString * s = @"purpleDog";//2 将Dog替换为Cat  NSString * s1 = [s stringByReplacingOccurrencesOfString:@"Dog" withString:@"Cat"]; //3 输出打印       NSLog(@"%@",s1);

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