PHP base echo, print, print_rvar_dump Difference Comparison

PHP Basics tutorial: (basic) Comparison between echo, print, print_r, printf, sprintf, var_dump

first, Echo

Echo () is not actually a function, it is a PHP statement, so you do not need to use parentheses on it. however, if you want to pass more than one argument to echo (), A parse error occurs when you use Parentheses. and echo returns void and does not return a value, so it cannot be used to assign a Value.

Example:

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second, Print

Print () is the same as Echo (), but the echo speed is a little bit faster than print. It is not actually a function, so you do not need to use parentheses on it. however, if you want to pass more than one parameter to print (), A parse error occurs when you use Parentheses. Note that print always returns 1, which is different from echo, which means you can use print to assign a value, but it doesn't make sense.

Example:

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three, Print_r function

The Print_r function prints easy-to-understand information about Variables.

Syntax: mixed Print_r (mixed $expression [, bool Return])

If the variable is a string, the integer or float will output its value directly, and if the variable is an array, it will output a formatted array for readability, which is the format of the key and Value. Similar for object Objects. Print_r has two parameters, the first is a variable, the second can be set to true, and if set to true, returns a string, otherwise returns a Boolean value of True.

Example:

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four, printf function

The printf function returns a formatted STRING.

Syntax: printf (format,arg1,arg2,arg++)

The parameters format is the converted format, starting with the percent sign ("%") to the end of the converted Character. The following is the possible format value:

*%%– return percent symbol

*%b– binary number

*%c– characters in accordance with ASCII values

*%d– Signed decimal number

*%e– Counting Method (E.G. 1.5e+3)

*%u– unsigned decimal number

*%f– floating point (local settings Aware)

*%f– floating point number (not Local Settings Aware)

*%o– octal number

*%s– string

*%x– Hexadecimal number (lowercase Letter)

*%x– Hexadecimal number (capital Letter)

arg1, arg2, arg++, etc. parameters will be inserted into the main string percent percent (%) Symbol. The function is executed incrementally, in the first% symbol, insert arg1, Insert arg2 at the second% symbol, and so On. If the% symbol is more than the ARG parameter, you must use a placeholder. After the placeholder is inserted in the% symbol, It consists of a number and a "\$". You can use numbers to specify the parameters that are displayed, see examples for Details.

Example:

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five, sprintf function

This function uses the same method as printf, except that the function writes the formatted string to a variable instead of the Output.

Example:

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vi.. var_dump function

Function: the content, type, and length of the output Variable's contents, type, or String. Commonly used to Debug.

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PHP base echo, print, print_rvar_dump Difference Comparison