"; $c=$a*$b; echo "$c
"; $c=$a/$b; echo "$c
";
$c=$a%$b; echo "$c
"; $c=++$a; echo "$c
"; $c=--$a; echo "$c
"; $c=$b++; echo "$c
"; $c=$b--; echo "$c
"; ?> 4. 理解赋值运算 "; $a+=5; echo "$a
"; $a-=5; echo "$a
"; $a*=5; echo "$a
"; $a/=5; echo "$a
"; $a%=5; echo "$a
"; $a="PHP"; $a.="程序设计"; echo "$a
"; ?> 5. 求 1+2+3…+100 的值。 "; ?> 6. 算术函数 abs 函数 $a=-12.3; $b=0; $c=23; $a=abs($a); $b=abs($b); $c=abs($c); $d=abs("12abcde12"); $e=abs("abcde"); echo "\$a=$a
"; echo "\$b=$b
"; echo "\$c=$c
"; echo "\$d=$d
"; echo "\$e=$e
"; ?> max 函数 "; echo "\$b1=$b1
"; echo "\$c1=$c1
"; echo "\$d1=$d1
"; ?> round 函数 \n"; echo "round(3.5): ".$foo2."
\n"; echo "round(3.6): ".$foo3; ?>