What is the difference between php printf and echo?

The difference between printf and echo in php: 1. echo is a command that can output multiple variables, such as "echo $a,$b;"; 2. printf is a function that can output formatted String, for example "printf("Variable a is %u, b is a %s",$a,$b);".

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echo can output multiple variables

<?php
$a=1;
$b=2;
echo $a,$b;
?>

echo is a command and cannot return a value. Echo can be followed by many parameters, separated by semicolons, such as:

echo $myvar1;
echo 1,2,$myvar,"bold";

print can only output one variable at a time

print is a function and can return A value can only have one parameter.

<?php
	$a=1;
	$b=2;
	print $a;
	print $b;
?>

printf is a mixture of static text and variables

The printf function formats the text and outputs it. For example:

<?php
$a=1;
$b="变量";
printf("变量a为%u，b是一个%s",$a,$b)
?>

The result is

Possible format values ​​in printf:

%% - Returns a percent sign %

%b - Binary number

%c - Character corresponding to the ASCII value

%d - Decimal number containing a plus or minus sign (negative number , 0, positive number)

%e - Use lowercase scientific notation (for example, 1.2e 2)

%E - Use uppercase scientific notation (for example, 1.2E 2)

%u - Decimal number without sign (greater than or equal to 0)

%f - Floating point number (local setting)

%F - Floating point number (non-local setting) )

%g - Shorter %e and %f

%G - Shorter %E and %f

%o - Octal number

%s - string

%x - hexadecimal number (lower case letters)

%X - hexadecimal number (upper case letters)

Additional formats value. Must be placed between % and a letter (such as %.2f):

(Add or - in front of the number to define the sign of the number. By default, only negative numbers are marked, and positive numbers are not marked. )

' (Specifies what to use as padding, defaults to spaces. It must be used with a width specifier.)

-(Left adjustment variable value)

[0 -9] (Specifies the minimum width of the variable value)

.[0-9] (Specifies the number of decimal places or the maximum string length)

Note: If you use more than one of the above format values, they must be used in the order above and cannot be disrupted

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