How to query data type in php?

How to query the data type in php: 1. Use "gettype (pass in a variable var)" to display the type of variable var; 2. Use "var_dump (pass in a variable var)" to display the variable var type; 3. Use the "is_*" series of functions to determine whether the variable is of the specified type, and return true if so.

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View data types

1. gettype(pass in a variable) can get the type of the variable
2. var_dump(pass in a variable) output the variable type and value

<?php
 //声明一个变量88.8，你可以自己多做几次实验换成其他类型看看$type输出是多少
 $float = 88.8;
 $type = gettype($float);
 echo $type;

 //多换几个类型试试
 $str = '你喜欢尊上还是喜欢杀仟陌？';
 var_dump($str);

Judge data type

We use the is_* series of functions. The is_types series of functions are used to determine whether something is of a certain type. Returns true if it is of this type, false if it is not.

Function	Analysis
is_int	is Integer
is_bool	Is it a Boolean
is_float	Is it a floating point
is_string	Is it a string
is_array	Is it an array
is_object	Is it an object
is_null	Is it empty
is_resource	Is it a resource
is_scalar	Is it a scalar
is_numeric	Is it Is the numeric type
is_callable	Is it a function

<?php
//is_* 系列函数有个特点，就是如果是这个类型就返回的是真。不是这个数据类型就返回的是假
//声明类型为假
$fo = false;

if(is_bool($fo)){
    echo '执行真区间';
}else{
    echo '执行假区间';
}

//检查未声明的变量$p是否为空，为空就执行真区间
if(is_null($p)){
    echo '执行真区间';
}else{
    echo '执行假区间';
}

//字符串类型的数值，看看执行的是真还是假
$str = '18.8';
if(is_numeric($str)){
    echo '执行真区间';
}else{
    echo '执行假区间';
}


//把sca的值换成整型、浮点、布尔和字符串试试
$sca = true;
//如果为标量，执行真区间
if(is_scalar($sca)){
    echo '执行真区间';
}else{
    echo '执行假区间';
}

//换成echo,is_int试试，为什么echo执行假区间呢？
if(is_callable('var_dump')){
    echo '执行真区间';
}else{
    echo '执行假区间';
}

Note: istypes is easy to remember. Just follow the type before and after is.

Scalar: int, float, bool, string

Mixed types: array, object

Special types: null, resource, callback

Why did echo execute a false interval in the final experiment?
Answer: Because echo is not a function, it is basic syntax. You don’t need to understand the difference between functions and basic syntax right now. Understanding and not understanding have no impact in actual development. Just know that you have this knowledge.

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