The Road to PHP Master (3)

Use str-replace instead of ereg-replace
Programmers who are used to programming in Perl are more willing to use ereg_replace to complete string replacement work, because the usage of ereg_replace in php is similar to the usage of pattern matching in Perl. However, the code below proves that using str_replace instead of ereg_replace will greatly improve the speed of the code.

Test the running speed of str_replace and ereg_replace

//This code tests the running speed of str_replace


emphasis; ?>

for (＄i=0; ＄i<1000; ＄i＋ +) {
str_replace( i>, b>, ＄string).
;
}
?>

//This code tests the running speed of ereg_replace




for (＄i=0; ＄i<100 0; $i++) {
ereg_replace(<([/]＊)i>, <\1b>, ＄string).
;
}
?>






//Print results


Conclusion

Time to use str_replace -


Time to use ereg_pattern -
Running the above code, the result is:
Time to use str_replace - 0.089757
Time to use ereg_pattern - 0.248881
From the running results we can see that str_replace is used instead ereg_replace, as a string replacement function, greatly improves the running speed of the code.
3. Pay attention to string quotation
Like many other programming languages, PHP can use double quotes ("") to quote strings, or single quotes (). But in PHP, if you use double quotes to quote a string, the PHP parser will first analyze whether there is a reference to a variable in the string. If there is a variable, it will replace the variable. If it is single quotes, it is not so complicated - all strings enclosed in single quotes are directly displayed. Obviously, in PHP programming, it is faster to use single quotes to quote string variables than double quotes.
4. Avoid using joint operations in the database
Compared with other web programming languages, PHP’s database function is very powerful. However, running the database in PHP is still a very time-consuming and labor-intensive matter. Therefore, as a Web programmer, you must minimize database query operations and establish appropriate indexes for the database. Another thing worth noting is that when using PHP to operate a database, try not to use joint operations of multiple data tables. Although joint operations can enhance the query function of the database, it greatly increases the burden on the server.
To illustrate this problem, we can look at the simple example below.
We created two data tables foo and big_foo in the database. In the data table foo, there is only one field, which contains all natural numbers from 1 to 1000. The data table big_foo also has only one field, but contains all natural numbers from 1 to 1,000,000. So, in terms of size, big_foo is equal to foo combined with itself.
＄db－>query("select ＊ from foo");
0.032273 secs
＄db－>next_record();
0.00048999999999999 secs
＄db－>query ("insert into foo values ​​(NULL)") ;
0.019506 secs
＄db－>query("select ＊ from foo as a, foo as b");
17.280596 secs
＄db－>query("select ＊ from foo as a, foo as b where a .id > b.id");
14.645251 secs
＄db－>query("select ＊ from foo as a, foo as b where a.id = b.id");
0.041269 secs
＄db－ >query("select ＊ from big_foo");
25.393672 secs
From the above operation results, we can find that the speed of joining two data tables with 1,000 records is not as fast as that of a large data table with 1,000,000 records. How much faster is it to do it alone.
5. Pay attention to the difference between include and require
In PHP programming, include() and require() have the same function, but there are some differences in usage. include() is a conditional inclusion function, while require() is an unconditionally included function. For example, in the following example, if the variable $somgthing is true, the file somefile will be included:
if(＄something){
include("somefile");
}
But no matter what value $something takes, the following code will include the file somefile into the file:
if(＄something){
require("somefile" );
}
The following interesting example fully illustrates the difference between these two functions.
＄i = 1;
while (＄i < 3) {
require("somefile.＄i");
＄i＋＋;
}
In this code, every time it loops, the program will included in the same file. Obviously this is not the programmer's original intention. From the code we can see that this code hopes to include different files in each loop. If you want to complete this function, you must turn to the function include():
＄i = 1;
while (＄i < 3) {
include("somefile.＄i");
＄i＋＋;
}
6. Note The difference between echo and PRint
The functions of echo and print in PHP are basically the same, but there are subtle differences between the two. You can use print as a normal function in PHP code. For example, after executing the following code, the value of the variable $res will be 1.
＄ret = print "Hello World";
This means that print can be used in some complex expressions, but echo cannot. Similarly, the echo statement in the code runs slightly faster than the print statement, because the echo statement does not require any value to be returned

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