freeCodeCamp/guide/english/php/php-strings/index.md

---
title: PHP strings
---

They are sequences of characters, like "PHP supports string operations".

NOTE − Built-in string functions is given in function reference PHP String Functions

Following are valid examples of string

$string_1 = "This is a string in double quotes";
$string_2 = "This is a somewhat longer, singly quoted string";
$string_39 = "This string has thirty-nine characters";
$string_0 = ""; // a string with zero characters
Singly quoted strings are treated almost literally, whereas doubly quoted strings replace variables with their values as well as specially interpreting certain character sequences.

```
<?php
   $variable = "name";
   $literally = 'My $variable will not print!\\n';
   
   print($literally);
   print "<br />";
   
   $literally = "My $variable will print!\\n";
   
   print($literally);
```

This will produce the following result −

```
My $variable will not print!\n
My name will print
```

There are no artificial limits on string length - within the bounds of available memory, you ought to be able to make arbitrarily long strings.

Strings that are delimited by double quotes (as in "this") are preprocessed in both the following two ways by PHP −

Certain character sequences beginning with backslash (\) are replaced with special characters

Variable names (starting with $) are replaced with string representations of their values.

The escape-sequence replacements are −

\n is replaced by the newline character
\r is replaced by the carriage-return character
\t is replaced by the tab character
\$ is replaced by the dollar sign itself ($)
\" is replaced by a single double-quote (")
\\ is replaced by a single backslash (\)

### String Concatenation Operator
To concatenate two string variables together, use the dot (.) operator −

```
<?php
   $string1="Hello World";
   $string2="1234";
   
   echo $string1 . " " . $string2;
```

This will produce the following result −

```
Hello World 1234
```

If we look at the code above you see that we used the concatenation operator two times. This is because we had to insert a third string.

Between the two string variables we added a string with a single character, an empty space, to separate the two variables.

### Using the strlen() function
The strlen() function is used to find the length of a string.

Let's find the length of our string "Hello world!":

```
<?php
   echo strlen("Hello world!");
```

This will produce the following result −

```
12
```

The length of a string is often used in loops or other functions, when it is important to know when the string ends. (i.e. in a loop, we would want to stop the loop after the last character in the string)

### Using the strpos() function
The strpos() function is used to search for a string or character within a string.

If a match is found in the string, this function will return the position of the first match. If no match is found, it will return FALSE. For this reason, it is important to always perform a strict comparison (===) to determine if a match is present.

Let's see if we can find the string "world" in our string −

```
<?php
   echo strpos("Hello world!","world");
```

This will produce the following result −

```
 6
```

As you see the position of the string "world" in our string is position 6. The reason that it is 6, and not 7, is that the first position in the string is 0, and not 1.

Let's see if we can find the string "Hello" in our string - 

```
<?php
   echo strpos("Hello world!", "world");
```

This will produce the following result - 

```
0
```

At first, this seems harmless, but let's take a look at another example -

```
<?php
   if (strpos("Hello world!", "Hello")) {
      echo 'The substring was found!';
   } else {
      echo 'The substring was not found...';
   }
```

Since this equates to '0', or falsy, this will produce the following result - 

```
   The substring was not found...
```

Instead, the following should always be used when using strpos() -

```
<?php
   if (strpos("Hello world!", "Hello") === false) {
      echo 'The substring was found!';
   } else {
      echo 'The substring was not found...';
   }
```

This will produce the following result -

```
   The substring was found!
```