/*************by garcon1986*********/
//The difference between print and echo:
//1. Echo can input multiple strings, but print cannot .
print "hello"."world"; //Success
echo "hello"."world"; //Success
//print "hello","world"; //Failure
echo "hello","world"; //Success
//2. Echo is faster than print.
$stime = microtime(true);
print "hello"."world";
$etime = microtime(true);
$total = $etime - $stime;
echo $total.'
';
//microtime — Return current Unix timestamp with microseconds
$stime2 = microtime(true);
echo "hello"."world";
$etime2 = microtime(true);
$total2 = $etime2 - $stime2;
echo $total2.'
';
//Execution result:
// helloworld0.0014331340789795
//helloworld0.00018310546875
//See echo is faster than print.
//print_r — Prints human-readable information about a variable or array
$a = "sajfd sfjal sfjalwureoi weu sj we fk io ";
print_r($a);
echo '';
$a = array("b","c","d");
print_r($a);
echo '
';
//var_dump — Dumps information about a variable or array
//var_dump -- Prints information about a variable
$a = "sajfd sfjal sfjalwureoi weu sj we fk io ";
var_dump($a );
echo '
';
$a = array("b","c","d");
var_dump($a);
echo '
';
var_dump(array("b","c","d"));
echo '
';
?>
/***********by garcon1986*******/
//%% - Returns the percent symbol
//%b - Binary number
//%c - Character according to ASCII value
//%d - signed decimal number
//%e - continuous counting method (such as 1.5e+3)
//%f - floating point number (local settings aware)
//% F - floating point number (not local settings aware)
//%o - octal number
//%s - string
//%u - unsigned decimal number
//%x - Hexadecimal number (lowercase letters)
//%X - Hexadecimal number (uppercase letters)
//printf() function outputs a formatted string
$str = "hello" ;
$number = 456;
//example1
printf("%s world. Day number %s", $str, $number); //Output: hello world. Day number 456
print "
";
//example2
printf("%%", $number); //%
print "
";
printf("%b", $number); //111001000
print "
";
printf("%c", $number); //ascii code
print "
";
printf("%d", $number); //456
print "
";
printf("%e", $number ); //4.560000e+2
print "
";
printf("%f", $number); //456.000000
print "
" ;
printf("%F", $number); //456.000000
print "
";
printf("%o", $number); //710
print "
";
printf("%s", $number); //456
print "
";
printf("%u" , $number); //456
print "
";
printf("%x", $number); //1c8
print "
" ;
printf("%X", $number); //1C8
print "
";
printf("With 2 decimals: %1$.2f
",$number);
//With 2 decimals: 456.00
//With no decimals: 456
printf("With 2 decimals: %f
With no decimals: %1$u
",$number);
//With 2 decimals: 456.000000
//With no decimals: 456
/ The /fprintf() function writes a formatted string to the specified output stream (for example: file or database).
$file = fopen("text.txt","w");
echo fprintf($file, "fprintf 1: %s world. Day number %u", $str, $number).'
'; //38
echo fprintf($file, "fprintf 2: %f", $number).'
'; //21
echo fprintf( $file,"fprintf 3: With 2 decimals: %1$.2fnWith no decimals: %1$u",$number).'
'; //56
//vprintf() function Output a formatted string.
//The arg parameter in vprintf() is in an array. The elements of the array are inserted into the main string at the percent (%) sign. This function is executed step by step. At the first % sign, arg1 is inserted, at the second % sign, arg2, and so on.
vprintf("vprintf: %s world. Day number %u", array($str,$number)); //vprintf: hello world. Day number 456
echo '
' ;
//sprintf() function writes the formatted string into a variable.
$txt = sprintf("sprintf: %s world. Day number %u",$str,$number);
echo $txt.'
'; //sprintf: hello world. Day number 456
//vfprintf() Operates as fprintf() but accepts an array of arguments, rather than a variable number of arguments.
echo vfprintf($file, "vfprintf: %s world! Day number %u", array($str, $number)).'
'; //37
//vsprintf() Operates as sprintf() but accepts an array of arguments, rather than a variable number of arguments.
$txt = vsprintf("vsprintf: %s world. Day number %u",array($str,$number));
echo $txt.'
'; //vsprintf: hello world. Day number 456
?>

php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($number))”;2、利用“~”位运算符将负数取反加一,语法“~$number + 1”。

实现方法:1、使用“sleep(延迟秒数)”语句,可延迟执行函数若干秒;2、使用“time_nanosleep(延迟秒数,延迟纳秒数)”语句,可延迟执行函数若干秒和纳秒;3、使用“time_sleep_until(time()+7)”语句。

php字符串有下标。在PHP中,下标不仅可以应用于数组和对象,还可应用于字符串,利用字符串的下标和中括号“[]”可以访问指定索引位置的字符,并对该字符进行读写,语法“字符串名[下标值]”;字符串的下标值(索引值)只能是整数类型,起始值为0。

php除以100保留两位小数的方法:1、利用“/”运算符进行除法运算,语法“数值 / 100”;2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值,并保留两位小数。

判断方法:1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式;2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的,因此真实天数需要在此基础上加1。

在php中,可以使用substr()函数来读取字符串后几个字符,只需要将该函数的第二个参数设置为负值,第三个参数省略即可;语法为“substr(字符串,-n)”,表示读取从字符串结尾处向前数第n个字符开始,直到字符串结尾的全部字符。

方法:1、用“str_replace(" ","其他字符",$str)”语句,可将nbsp符替换为其他字符;2、用“preg_replace("/(\s|\ \;||\xc2\xa0)/","其他字符",$str)”语句。

查找方法:1、用strpos(),语法“strpos("字符串值","查找子串")+1”;2、用stripos(),语法“strpos("字符串值","查找子串")+1”。因为字符串是从0开始计数的,因此两个函数获取的位置需要进行加1处理。


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