objective-c - C语言或OC或C++ 中英文混合的文件读取前3个字符怎么做？

Question

1.txt 文件内容： 你好a,我是千叶！ 期望结果： 你好a {代码...} ==================================================================================== 我的场景是文件比较大，不太想把整个文件读取到NSData...

天蓬老师 · Answer

Give me an idea:

To read files, you must know the character encoding
Generates an NSString object. NSString has an initialization method initWithData:encoding:, and NSData has an initialization method dataWithContentsOfFile:
After ensuring that step axis 2 generates the object normally, call the member method of NSString: substringWithRange:Interception

Hope this helps lz

ringa_lee · Answer

The key point of the problem is: Under the conditions of ANSI encoding, one Chinese character occupies two bytes and one English character occupies one byte .

So for your example:

// 1.txt
你好a,我是千叶！
^^^^^
// "你好a", 数一数，是5个字节。

So if you want to intercept "Hello a", then use:

cfread(x,sizeof(char),5,fp);
printf("%s
", x); // 输出 "你好a"

If it is all in Chinese, for example:

// 1.txt
你好啊,我是千叶！
^^^^^^
// 三个汉字是 6 个字节

Then if you want Chinese characters not to be truncated, you should at least read an even number of bytes.

cfread(x,sizeof(char),6,fp);
printf("%s
", x); // 输出 "你好啊"

伊谢尔伦 · Answer

This depends on the encoding. If the encoding standard is not certain, I am afraid that any software will read garbled characters.

PHP中文网 · Answer

...I’m not sure if I’m talking about the same thing as you...
It's nothing more than a problem with Chinese characters. You can directly take the length of the first 6 characters (regardless of Chinese and English, 6 characters are always enough), convert it into NSString, and then directly substringToIndex:3, take the first three characters, and it will come out. ?