The difference between php output functions

Comparison of the differences between php output echo, print, print_r, printf, sprintf, var_dump and other functions

##echo, Language structure, non-function, can have multiple values ​​without parentheses, separated by commas. Integer and string, Boolean type will be converted to 1 or empty, no return value (recommended learning: PHP programming from entry to proficiency)

echo() is not actually a function, it is php statement so you don't need to use brackets on it. However, if you wish to pass more than one argument to echo(), then using parentheses will cause a parsing error. Moreover, echo returns void and does not return a value, so it cannot be used to assign values.

print, language structure, non-function, can only have one parameter value, slower than echo. The printing type is the same as echo, and there is no return value.

The usage of print() and echo() is the same, but the echo speed is a little faster than print. It's actually not a function either, so you don't need to use parentheses on it.

print_r can output integers, strings, arrays, and objects. The second parameter is set to true and the print content is returned.

The print_r function prints information about variables. Easy to understand information.

mixed print_r ( mixed $expression [, bool return ] )

If the variable is string, integer or float, its value will be output directly. If the variable is an array, a formatted array will be output for easy reading, that is, there are corresponding keys and values. That format. The same is true for object objects.

print_r has two parameters, the first is a variable, and the second can be set to true. If set to true, a string will be returned, otherwise a Boolean value TRUE will be returned.

sprintf, write the formatted string into the variable, return the formatted string

printf, output the formatted String, no return value

fprintf, writes the formatted string to the specified output stream (for example: file or database), no return value

vfprintf, writes the formatted string to the specified output stream (for example: file or database), the parameter is an array, no return value

vprintf, output format formatted string, the parameters are located in the array, no return value

vsprintf, write the formatted string into the variable, the parameters are located in the array, return the formatted string

var_dump, you can print multiple variables and their types, separated by commas, you can print Boolean values, no return value

var_export, return Legal php code, you can print Boolean values. The second parameter is set to true, and the printed content can be returned to the variable

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