如何在 PHP 中將字串轉換為數字
Minahil Noor
2023年1月30日
2020年6月9日
在本文中，我們將介紹在 PHP 中將字串轉換為數字的方法。
- 使用顯式型別轉換
- 使用
intval()/floatval()函式 - 使用
settype()函式
在 PHP 中使用顯式型別轉換將字串轉換為數字
顯式型別轉換將任何型別的變數轉換為所需型別的變數。它將變數轉換為原始資料型別。將變數顯式型別轉換為 int 或 float 的正確語法如下
$variableName = (int)$stringName
$variableName = (float)$stringName
變數 $variableName 是整數變數，用於儲存 number 的值。變數 $stringName 是數字字串。我們還可以將非數字字串轉換為數字。
<?php
$variable = "10";
$integer = (int)$variable;
echo "The variable $variable has converted to a number and its value is $integer.";
echo "\n";
$variable = "8.1";
$float = (float)$variable;
echo "The variable $variable has converted to a number and its value is $float.";
?>
輸出：
The variable 10 has converted to a number and its value is 10.
The variable 8.1 has converted to a number and its value is 8.1.
對於非數字字串，我們將得到 0 作為輸出。
<?php
$variable = "abc";
$integer = (int)$variable;
echo "The variable has converted to a number and its value is $integer.";
?>
輸出：
The variable has converted to a number and its value is 0.
在 PHP 中使用 intval() 函式將字串轉換為數字
intval() 函式將字串轉換為整型 int。
floatval() 函式將字串轉換為浮點數 float。
這些函式接受的引數是一個字串，返回值分別是一個整數或一個浮點數。
intval( $StringName );
變數 StringName 是字串型別。
<?php
$variable = "53";
$integer = intval($variable);
echo "The variable $variable has converted to a number and its value is $integer.";
echo "\n";
$variable = "25.3";
$float = floatval($variable);
echo "The variable $variable has converted to a number and its value is $float.";
?>
輸出：
The variable 53 has converted to a number and its value is 53.
The variable 25.3 has converted to a number and its value is 25.3.
如果給定的字串是數字和字串表示形式的混合，例如 2020Time，則 intval() 將返回 2020。但是，如果給定的字串不是以數字開頭，則它將返回 0。floatval() 方法也是如此。
示例程式碼：
<?php
$variable = "2020Time";
$integer = intval($variable);
echo "The variable $variable has converted to a number and its value is $integer.";
echo "\n";
$variable = "Time2020";
$integer = intval($variable);
echo "The variable $variable has converted to a number and its value is $integer.";
echo "\n";
$variable = "25.3Time";
$float = floatval($variable);
echo "The variable $variable has converted to a number and its value is $float.";
echo "\n";
$variable = "Time25.3";
$float = floatval($variable);
echo "The variable $variable has converted to a number and its value is $float.";
?>
輸出：
The variable 2020Time has converted to a number and its value is 2020.
The variable Time2020 has converted to a number and its value is 0.
The variable 25.3Time has converted to a number and its value is 25.3.
The variable Time25.3 has converted to a number and its value is 0.
在 PHP 中使用 settype() 函式將字串轉換為數字
settype() 函式將任何資料型別的變數轉換為特定資料型別。它接受兩個引數，變數和型別名稱。
settype($variableName, "typeName");
$variableName 是我們要轉換為數字的任何資料型別的變數。"typeName" 是我們要為 $variableName 變數使用的資料型別的名稱。
<?php
$variable = "45";
settype($variable, "integer");
echo "The variable has converted to a number and its value is $variable.";
?>
settype() 函式將 $variable 的型別從字串設定為整型 integer。它僅適用於原始資料型別。
輸出：
The variable has converted to a number and its value is 45.
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