


Explanation of the meaning of common PHP error prompts (practical! Worth collecting), error prompts are worth collecting
This article explains the meaning of common PHP error prompts. Share it with everyone for your reference, the details are as follows:
When I was learning PHP, I often encountered various error prompts. It felt good to see this error prompt and explanation today. I now turn it over for us to learn from. hehe. . . . .
1. Notice: Undefined variable: variable name in
Note: An undefined variable is used
2. Parse error: syntax error, unexpected T_ELSE in
If () {
}Else if () {
}
Echo $test;
Else {
}
Note: The if else if else sentence structure is wrong
3. Parse error: syntax error, unexpected $end in D
Note: Usually the curly braces do not match
4. Parse error: syntax error, unexpected T_STRING in
Note: Usually I forget to write the semicolon at the end of the sentence
5. Warning: Invalid argument supplied for foreach() in
Note: the first parameter of foreach must be an array
6. Warning: mysql_fetch_assoc(): supplied argument is not a valid MySQL result resource in
Note: This means that the previous execution of SQL failed to return. Generally, it may be an error in the SQL statement. If the analysis cannot come out, you can just print out Mysql_error (); to see where the error is specifically
7. No database selected
Note: Usually there is no connection to the database
8. Warning: mysql_connect() [function.mysql-connect]: Access denied for user 'root'@'localhost' (using password : YES) in ….. on line 3
Access denied for user 'root'@'localhost' (using password: YES)
Note: The database username and password are wrong
9. Unknown database 'cms07261′
Note: There is no such database
10. Table 'cms0726.test' doesn't exist
Note: The table does not exist
11. Unknown column 'abc' in 'field list'
Note: Field does not exist
12. Column count doesn't match value count at row 1
Note: The number of field values in the sql statement is different from the number of field names
13. Warning: Wrong parameter count for function name in
Note: The number of function logarithms is missing
14. Fatal error: Smarty error: [in message_list.html line 22]: syntax error: 'foreach: item' must be a variable name (literal string)
Note: Look at the line number, it means that the item after foreach must be followed by a variable name, without $, it is a string (note: no single or double quotes)
15. Fatal error: Smarty error: [in message_list.html line 24]: syntax error: unrecognized tag: msg.message_id
Note: $
16. Warning: Smarty error: unable to read resource: "message_list1.html" in
Note: The template file cannot be found. Check whether the file name is written incorrectly or the file is stored in another directory.
17. Fatal error: Cannot redeclare get_sort1() (previously declared in
Note: The function has been defined and cannot be redefined
I hope this article will be helpful to everyone in PHP programming.

php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($number))”;2、利用“~”位运算符将负数取反加一,语法“~$number + 1”。

实现方法:1、使用“sleep(延迟秒数)”语句,可延迟执行函数若干秒;2、使用“time_nanosleep(延迟秒数,延迟纳秒数)”语句,可延迟执行函数若干秒和纳秒;3、使用“time_sleep_until(time()+7)”语句。

php除以100保留两位小数的方法:1、利用“/”运算符进行除法运算,语法“数值 / 100”;2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值,并保留两位小数。

判断方法:1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式;2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的,因此真实天数需要在此基础上加1。

php字符串有下标。在PHP中,下标不仅可以应用于数组和对象,还可应用于字符串,利用字符串的下标和中括号“[]”可以访问指定索引位置的字符,并对该字符进行读写,语法“字符串名[下标值]”;字符串的下标值(索引值)只能是整数类型,起始值为0。

方法:1、用“str_replace(" ","其他字符",$str)”语句,可将nbsp符替换为其他字符;2、用“preg_replace("/(\s|\ \;||\xc2\xa0)/","其他字符",$str)”语句。

php判断有没有小数点的方法:1、使用“strpos(数字字符串,'.')”语法,如果返回小数点在字符串中第一次出现的位置,则有小数点;2、使用“strrpos(数字字符串,'.')”语句,如果返回小数点在字符串中最后一次出现的位置,则有。

在php中,可以使用substr()函数来读取字符串后几个字符,只需要将该函数的第二个参数设置为负值,第三个参数省略即可;语法为“substr(字符串,-n)”,表示读取从字符串结尾处向前数第n个字符开始,直到字符串结尾的全部字符。


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