Question

有没有人知道在NSString或相同字符的NSArray中查找字符的速度更有效？

我想知道哪种算法具有最佳和最有效的算法来找到正确的值。

我实际上想要找到字母表中字符的位置。例如在字母E或@"ABCDE....XYZ"

中找到“[NSArray arrayWithObjects:@"A",@"B",@"C",@"D",@"E",...,@"X",@"Y",@"Z"];”的位置

哪个搜索更好？ NSString或NSArray？

Answer 1

如果它只是A-Z：

NSString *string = @"A";
int position = (int)[string characterAtIndex:0]-64;
NSLog(@"%d", position);

出于好奇：

NSString *alphabetString = @"ABCDEFGHIJKLMNOPQRSTUVWXYZ";
NSMutableArray *alphabetArray = [NSMutableArray array];
for(int pos = 0; pos < [alphabetString length]; pos++) {

    [alphabetArray addObject:[alphabetString substringWithRange:NSMakeRange(pos, 1)]];
}

NSString *check = @"A";

// check with rangeOfString
NSDate *start = [NSDate date];
for(int i = 0; i < 1000000; i++) {

    int position = [alphabetString rangeOfString:check].location + 1;
}
NSDate *end = [NSDate date];
NSLog(@"STRING | time needed: %f", [end timeIntervalSinceDate:start]);

// check with indexOfObject
start = [NSDate date];
for(int i = 0; i < 1000000; i++) {

    int position = [alphabetArray indexOfObject:check] + 1;
}
end = [NSDate date];
NSLog(@"ARRAY | time needed: %f", [end timeIntervalSinceDate:start]);

// check with ASCII position
start = [NSDate date];
for(int i = 0; i < 1000000; i++) {

    int position = (int)[check characterAtIndex:0]-64;
}
end = [NSDate date];
NSLog(@"ASCII | time needed: %f", [end timeIntervalSinceDate:start]);

控制台：

STRING | time needed: 0.156067
ARRAY | time needed: 0.213297
ASCII | time needed: 0.017055

NSString与NSArray中角色的位置 - 性能/效率

1 个答案: