In this tutorial, you shall learn how to convert a PHP array into a JSON string using json_encode() function, with syntax and example programs.

PHP – Convert Array into JSON String

To convert an associative array into a JSON String in PHP, call json_encode() function and pass the associative array as argument. This function can take other optional parameters also that effect the conversion to JSON String.

Syntax

The syntax of json_decode() function is

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json_encode(value, flags, depth)

where

ParameterDescription
value[Required] The value which has to be encoded into a JSON String.
flags[Optional] Bitmask consisting of JSON_FORCE_OBJECT, JSON_HEX_QUOT, JSON_HEX_TAG, JSON_HEX_AMP, JSON_HEX_APOS, JSON_INVALID_UTF8_IGNORE, JSON_INVALID_UTF8_SUBSTITUTE, JSON_NUMERIC_CHECK, JSON_PARTIAL_OUTPUT_ON_ERROR, JSON_PRESERVE_ZERO_FRACTION, JSON_PRETTY_PRINT, JSON_UNESCAPED_LINE_TERMINATORS, JSON_UNESCAPED_SLASHES, JSON_UNESCAPED_UNICODE, JSON_THROW_ON_ERROR.
depth[Optional] Integer. Specifies the maximum depth. Default value = 512.

json_encode() returns a string, or false if the encoding is not successful.

Examples

1. Convert given Associative array into JSON string

In this example, we take an associative array and convert it into a JSON string using json_encode() function with the default optional parameters. We shall display the string returned by json_encode() in the output.

PHP Program

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<?php
$arr = array("apple" =>  25, "banana" => 41, "cherry" => 36);
$output = json_encode($arr);
echo $output;
?>

Output

PHP - Convert Array into JSON String

2. Convert nested Associative array into JSON string

In this example, we take a nested associative array, where the value for a key in the outer array is another array, and convert it into a JSON string using json_encode() function.

PHP Program

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<?php
$arr = array(
    "a" =>  25,
    "b" => 41,
    "c" => array(
        "d" => 12,
        "e" => 58
    ),
);
$output = json_encode($arr);
echo $output;
?>

Output

PHP - Convert Array into JSON String

Conclusion

In this PHP Tutorial, we learned how to convert an array into a JSON string, using json_encode() function.