The following code proves our conclusion. In this code, we use the time test function described above.
Use str-replace instead of ereg-replace
Programmers who are accustomed to programming with 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 following code proves that using str_replace instead of ereg_replace will greatly improve the running 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<1000; ＄i＋＋) {
ereg_replace(<([/]＊)i>, <\1b>, ＄string).
}
?>
//Print results
in conclusion
Time to use str_replace －
Time to use ereg_pattern －
Run the above code and the result is:
Time to use str_replace - 0.089757
Time to use ereg_pattern - 0.248881
From the results of the run, we can see that using str_replace instead of ereg_replace as a string replacement function greatly improves the running speed of the code.
3. Pay attention to the reference of strings
Like many other programming languages, PHP can use double quotes ("") to quote strings, or single quotes (). However, in PHP, if double quotes are used 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, the variable will be replaced. If it is single quotes, it is not so complicated - directly display all the strings contained in single quotes. Obviously, in PHP programming, it is faster to quote string variables using single quotes than to use double quotes.
4. Avoid using joint operations in the database
Compared with other web programming languages, PHP's database functions are very powerful. However, running a database in PHP is still a very time-consuming and laborious task. Therefore, as a web programmer, you should minimize database query operations and establish appropriate indexes for the database. Another thing worth noting is that when operating the database with PHP, do not use joint operations of multiple data tables as much as possible. 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 take a look at this 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 that 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 equals foo to operate in combination 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 > ");
14.645251 secs
＄db－>query("select ＊ from foo as a, foo as b where = ");
0.041269 secs
＄db－>query("select ＊ from big_foo");
25.393672 secs
From the above operation results, we can find that the speed of combining two data tables with 1000 records is not much faster than operating a large data table with 1000,000 records separately.
5. Pay attention to the difference between include and require
In PHP, include() and require() have the same functions, but their usage is somewhat different. include() is a conditional include function, while require() is an unconditional include function. For example, in one of the following examples, 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 in the file:
if(＄something){
require("somefile");
}
The interesting example below fully illustrates the difference between the two functions.
＄i = 1;
while (＄i < 3) {
require("somefile.＄i");
＄i＋＋;
}
In this code, every time the program loops, the program will include the same file. Obviously this is not the original intention of the programmer. 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 ask the function include():
＄i = 1;
while (＄i < 3) {
include("somefile.＄i");
＄i＋＋;
}
6. Pay attention to the difference between echo and print
The functions of echo and print in PHP are basically the same, but there are also slight differences between the two. In PHP code, print can be used as a normal function. 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, while echo cannot. Similarly, echo statements run slightly faster in the code than print statements, because echo statements do not require any numerical values to be returned.