OC基础语法

NSString *str=@"Hello Liu 永慧";
//计算字符串长度
NSLog(@"%lu",(unsigned long)str.length);
NSLog(@"%lu",(unsigned long)[str length]);
//获取单个字符
unichar c=[str characterAtIndex:0];
NSLog(@"c:%C",c);
//比较两个字符串是否相等
NSString *str1=@"hello";
NSString *str2=@"hello";
BOOL ret=[str1 isEqualToString:str2];
if (ret==YES) {
NSLog(@"str1==str2");
}
else
{
NSLog(@"str2!=str1");
}
//比较字符串的大小
str1=@"liu";
str2=@"yong";
NSComparisonResult cmp=[str1 compare:str2];
if (cmp==NSOrderedAscending) {
NSLog(@"左边小于右边");
}
else if (cmp==NSOrderedSame)
{
NSLog(@"相等");
}
else if (cmp==NSOrderedDescending)
{
NSLog(@"左边大于右边");
}