How to convert string array to numeric type in php

In PHP, strings are a common data type, and numbers are a basic data type. In development, we sometimes need to convert string arrays to numeric types in order to perform mathematical calculations or other numerical operations.

PHP provides several methods to convert string arrays to numeric types. These methods will be introduced below, and their applicable scenarios and usage methods will be explained.

1. Use type conversion functions

There are several type conversion functions in PHP that can convert strings into numbers, they are:

• intval(): Convert a string to an integer value.
• floatval(): Convert a string to a floating point value.
• doubleval(): Convert a string to a double-precision floating point value.

These functions can convert a string to the corresponding numeric type. For example:

$str = "123";
$int = intval($str);
$float = floatval($str);
$double = doubleval($str);

echo $int;    // 输出：123
echo $float;  // 输出：123.0
echo $double; // 输出：123.0

It should be noted that if the string contains non-numeric characters, the type conversion function will return 0.

2. Using casts

In PHP, we can use casts to convert variables from one type to another. The syntax of forced type conversion is as follows:

$new_var = (new_type) $old_var;

Among them, new_type represents the converted data type, and old_var represents the variable that needs to be converted. For example:

$str = "123";
$int = (int) $str;
$float = (float) $str;
$double = (double) $str;

echo $int;    // 输出：123
echo $float;  // 输出：123.0
echo $double; // 输出：123.0

The effect of forced type conversion is basically the same as that of the type conversion function, but forced type conversion is simpler and more direct.

It should be noted that if the string contains non-numeric characters, the cast will return 0.

3. Using array mapping functions

There are several array mapping functions in PHP that can convert each element in an array to another type, including:

• array_map(): Apply a function to each element of the array and return a new array.
• array_walk(): Apply a function to each element of the array, no return value.

These functions can convert each element in a string array to the corresponding numeric type. For example:

$arr = array("123", "456", "789");
$int_arr = array_map("intval", $arr);
$float_arr = array_map("floatval", $arr);
$double_arr = array_map("doubleval", $arr);

print_r($int_arr);    // 输出：Array([0] => 123 [1] => 456 [2] => 789)
print_r($float_arr);  // 输出：Array([0] => 123.0 [1] => 456.0 [2] => 789.0)
print_r($double_arr); // 输出：Array([0] => 123.0 [1] => 456.0 [2] => 789.0)

It should be noted that these functions will return 0 if the string contains non-numeric characters.

4. Using a foreach loop

In addition to using functions for type conversion, we can also use a foreach loop to traverse the array and convert each element to a numeric type. For example:

$arr = array("123", "456", "789");

foreach($arr as &$val) {
    $val = (int) $val;
}

print_r($arr);    // 输出：Array([0] => 123 [1] => 456 [2] => 789)

This method is more flexible and can be applied according to the actual situation.

Summary

In PHP, there are many methods to convert string arrays to numeric types, which are suitable for different application scenarios. Using type conversion functions and casts can quickly and easily convert a string to the corresponding numeric type, while using array mapping functions and foreach loops is suitable for situations where you need to traverse the entire array and perform the same operation on each element. Developers should choose the appropriate method for type conversion based on specific circumstances to improve code efficiency and readability.

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