C语言中谓词的用法

NSArray *persons = @[jack, tom, rose, lucy, bob, john, lily];

//指定谓词条件

NSPredicate *pre1 = [NSPredicate predicateWithFormat:@"age < 40"];

for (Person *person in persons) {

//条件匹配

//验证对象是否符合谓词pre1

BOOL bool1 = [pre1 evaluateWithObject:person];

if (bool1) {

NSLog(@"%@", person);

}

}

//初始化谓词

NSPredicate *pre = [NSPredicate predicateWithFormat:@"age < %d", 40];

//数组中的方法，将符合谓词条件的数据筛选出来，返回一个新数组

NSArray *filteredArr = [persons filteredArrayUsingPredicate:pre];

NSLog(@"filteredArr is %@", filteredArr);

//逻辑运算符

// 运算符号 的加入 谓词不区分大小 && AND || OR

NSPredicate *pre3 = [NSPredicate predicateWithFormat:@"name = ‘rose‘ && age < %d", 30];

NSArray *array4 = [persons filteredArrayUsingPredicate:pre3];

NSLog(@"array4 is %@", array4);

// 关键字 注意字符串一定要添加‘‘

NSPredicate *pre4 = [NSPredicate predicateWithFormat:@"name IN {‘rose‘, ‘bruse‘, ‘jack‘}"];

NSArray *array5 = [persons filteredArrayUsingPredicate:pre4];

NSLog(@"%@", array5);

//BEGINSWITH 检查某个字是否以**开头

NSPredicate *pre5 = [NSPredicate predicateWithFormat:@"self.name BEGINSWITH ‘j‘"];

NSArray *array6 = [persons filteredArrayUsingPredicate:pre5];

NSLog(@"%@", array6);

//ENDSWITH 检查某个字符是以**结尾

NSPredicate *pre6 = [NSPredicate predicateWithFormat:@"self.name endswith ‘e‘"];

NSArray *array7 = [persons filteredArrayUsingPredicate:pre6];

NSLog(@"%@", array7);

// CONTAINS 检查包含某个字符

NSPredicate *pre8 = [NSPredicate predicateWithFormat:@"self.name CONTAINS ‘os‘"];

NSArray *array8 = [persons filteredArrayUsingPredicate:pre8];

NSLog(@"%@", array8);