Recorded PHP daily attention points (1)

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Personally record some of your daily life When writing PHP code, some minor problems encountered will be updated from time to time;
Welcome everyone to point out the errors in the problem in time. You can mark the specific problem number when making comments. Thank you everyone and share your encouragement;

1, float data type output format problem

$float1 = 1.123;$float2 = 2.3e3;$float3 = 8E-5;var_dump($float1, $float2, $float3);    //float(1.123) float(2300) float(8.0E-5)var_dump(number_format(8E-5, 5));    //string(7) "0.00008"

You will find that 8E-5 is not output as 0.00008. This is because PHP will automatically convert some numbers with too many digits into Scientific notation displays

. At this time, if you want to output the format as 0.00008, you can use number_format(). Also note that this function returns string

2. After using the . splicing character, it is automatically converted to string type

$a = 12;$b = 1.3;$c = true;    //转为1var_dump($a . $b . $c);        //string(6) "121.31"

3, strlen(), strpos() Chinese character processing

strlen() returns the length of the string, in bytes, one for English and three for Chinese;
English is easy to say, no special processing is needed, while Chinese can use the special mb_strlen()

echo strlen('string');        //6echo strlen('你好！世界');    //15（5个中文字符*3）echo strlen('你好！PHP');     //12（三个中文字符*3 + 3个英文）echo mb_strlen('你好！世界');    //5echo mb_strlen('你好！PHP');     //6 每个都按字符算

strpos() is used to find whether a certain character appears in a specified string. If a match is found in the string, the function will return the first matching character position. If no match is found, returns FALSE.
It should be noted that: the first position of the string is 0, not 1;
Similarly, this function also has problems in Chinese and English, and it also requires a special mb_strpos() function to handle it

echo strpos("hello php", "php");    //6echo strpos("hello php","he");          //0echo strpos("你好，php", "p");    //9echo mb_strpos("你好，php", "p");    //3

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