double-quotes | 易学教程

Making a new line with single quotes?

阅读更多关于 Making a new line with single quotes?

问题 Can I do a line break like this '\n' ? Or do I must use double quotes - "\n" ? 回答1: You have to use double quotes. Otherwise, PHP will literally output \n . http://php.net/manual/en/language.types.string.php 回答2: To output a newline (or any other control character for that matter) you must always use double quotes. An alternative to not use double quotes is chr() with the respective ASCII code as an argument: echo chr(10); // same as echo "\n"; 回答3: just add .PHP_EOL; to the end of your line

Sqlite - Use backticks (`) or double quotes (") with python

阅读更多关于 Sqlite - Use backticks (`) or double quotes (") with python

问题 I saw a similar question in Stack Overflow pertaining to Android, but I was wondering whether I should use backticks (`) or double quotes (") - using Python - to select table names or rowid or what have you. I tried single quotes - like this select 'rowid', * from 'tbl' order by 'rowid' . The single quotes worked in some cases but not all. I learned to use double quotes or backticks, and I was looking at SQLite Database Browser and I noticed that it used backticks. I really like to put double

Is there any difference between “string” and 'string' in Python? [duplicate]

阅读更多关于 Is there any difference between “string” and 'string' in Python? [duplicate]

This question already has an answer here: Single quotes vs. double quotes in Python [closed] 19 answers In PHP, a string enclosed in "double quotes" will be parsed for variables to replace whereas a string enclosed in 'single quotes' will not. In Python, does this also apply? Milen A. Radev No : 2.4.1. String and Bytes literals ...In plain English: Both types of literals can be enclosed in matching single quotes ( ' ) or double quotes ( " ). They can also be enclosed in matching groups of three single or double quotes (these are generally referred to as triple-quoted strings). The backslash (

double quote escaping in os.system on windows

阅读更多关于 double quote escaping in os.system on windows

问题 I want to escape '"' and all other wild chars in program name and arguments, so I try to double quote them. and I can do this in cmd.exe C:\bay\test\go>"test.py" "a" "b" "c" hello ['C:\\bay\\test\\go\\test.py', 'a', 'b', 'c'] but what's wrong with the following code using os.sytem? cmd = '"test.py" "a" "b" "c"' print cmd os.system(cmd) its output: C:\bay\test\go>test2.py "test.py" "a" "b" "c" 'test.py" "a" "b" "c' is not recognized as an internal or external command, operable program or batch

How does the leading dollar sign affect single quotes in Bash?

阅读更多关于 How does the leading dollar sign affect single quotes in Bash?

I need to pass a string to a program as its argument from the Bash CLI, e.g program "don't do this" The string may include any character like '$' , '\' , etc. and I don't want Bash to do any modification. So I think about using single quotes. However the following does not work: program 'don\'t do this' //escape doesn't work in single quote While the following two works: program $'dont\'t do this' //seems fine, but any other side effects? program 'dont'\''do this' //breaking into 3 parts The first approach seems better in that it acquires less pre modification (put the dollar symbol in front

How to read \\\" double-quote escaped values with read.table in R

阅读更多关于 How to read \\\" double-quote escaped values with read.table in R

I am having trouble to read a file containing lines like the one below in R. "_:b5507F4C7x59005","Fabiana D\"atri" Any idea? How can I make read.table understand that \" is the escape of quote? Cheers, Alexandre It seems to me that read.table/read.csv cannot handle escaped quotes. ...But I think I have an (ugly) work-around inspired by @nullglob; First read the file WITHOUT a quote character. (This won't handle embedded , as @Ben Bolker noted) Then go though the string columns and remove the quotes: The test file looks like this (I added a non-string column for good measure): 13,"foo","Fab D\

Fixing column “columnname” does not exist pgsql in database. Double quote vs single quote error

阅读更多关于 Fixing column “columnname” does not exist pgsql in database. Double quote vs single quote error

问题 I have a table review(movie_id, user_id, reviewtext, date, time, likes, status)/ I get the error column "exist" does not exist LINE 1: INSERT INTO review values ($1, $2, $3,$4,$5 ,0,"exist") ^ ) when I want to insert values into a postgresql database. I can not modify the code anymore so is there any way to make this work by altering the database like adding a column? The code to insert is as follows: $query = $this->db->prepare('INSERT INTO review values (:movieid, :userid, :review,:date,

php to extract a string from double quote

阅读更多关于 php to extract a string from double quote

I have a string: This is a text, "Your Balance left $0.10", End 0 How can I extract the string in between the double quotes and have only the text (without the double quotes): Your Balance left $0.10 I have tried preg_match_all() but with no luck. As long as the format stays the same you can do this using a regular expression. "([^"]+)" will match the pattern Double-quote At least one non-double-quote Double-quote The brackets around the [^"]+ means that that portion will be returned as a separate group. <?php $str = 'This is a text, "Your Balance left $0.10", End 0'; //forward slashes are the

bash alias command with both single and double quotes

阅读更多关于 bash alias command with both single and double quotes

I have this command that does what I want but I can't get to alias it in my .bashrc (note that it uses both single and double quotes): svn status | awk '$1 =="M"{print $2;}' I've tried: alias xx="svn status | awk '$1 ==\"M\"{print $2;}'" And some other common sense combinations with no luck.. I know that bash is very picky with quotes.. So what's the correct way to alias it and why ? Thanks You just need to escape it correctly. alias xxx="svn status | awk '\$1 ==\"M\"{print \$2;}'" EJK Here's something that accomplishes the same thing without using an alias. Put it in a function in your

Add php variable inside echo statement as href link address?

阅读更多关于 Add php variable inside echo statement as href link address?

I'm trying to use a php variable to add a href value for a link in an echo statement. Here's a simplified version of the code I want to use. I know that I can't just add the variable into the echo statement, but I can't seem to find an example anywhere that works. $link_address = '#'; echo '<a href="$link_address">Link</a>'; Any pointers appreciated. Try like HTML in PHP : echo "<a href='".$link_address."'>Link</a>"; Or even you can try like echo "<a href='$link_address'>Link</a>"; Or you can use PHP in HTML like PHP in HTML : <a href="<?php echo $link_address;?>"> Link </a> you can either use