字符串
注意單引號(hào)和雙引號(hào)的區(qū)別
注意轉(zhuǎn)義字符\的使用\\,\",\$
注意使用8進(jìn)制或16進(jìn)制字符表示?\xf6
echo?"H\xf6me";//需要察看是否支持此類(lèi)文字編碼
---------------------輸出結(jié)果----------------------------------------
H鰉e
---------------------------------------------------------------------

1.使用printf()和sprintf()創(chuàng)建格式化的輸出

printf()直接輸出到輸出緩沖區(qū)
sprintf()的輸出作為字符串返回
如printf("輸出內(nèi)容?%.2f\n",$PI());
所有的轉(zhuǎn)換規(guī)范都以%開(kāi)頭
數(shù)據(jù)類(lèi)型有d-整數(shù),s-字符串,f-浮點(diǎn)數(shù),b-二進(jìn)制
.2是一個(gè)可選的寬度指標(biāo)，小數(shù)點(diǎn)右邊輸出使用0填充
printf("%.2f",3.14159);
printf("%10.2f",3.14159);
printf("%.10f",3.14159);
printf("%.9s",abcdefghijklmn);
printf("%5.2f,%f,%7.3f\m",3.14159,3.14159,3.14159);
printf("%b?%d?%f?%s?\n",123,123,123,"test");
---------------------輸出結(jié)果----------------------------------------
3.14?3.143.1415900000abcdefghi?3.14,3.141590,?3.142\m1111011?123?123.000000?test?
---------------------------------------------------------------------

2.字符串填充

string?str_pad(string?input原始字串,?int?length添加后的總長(zhǎng)度[,?string?padding要填充的字符?[,?int?pad_type]填充類(lèi)型])
填充類(lèi)型有添加在左邊STR_PAD_LEFT，默認(rèn)添在右邊，填充在兩端STR_PAD_BOTH
$index?=?array("one"=>1,"two"=>155,"three"=>1679);
echo?"
";
echo?str_pad("這是標(biāo)題",50,"?",STR_PAD_BOTH)."\n";
foreach($index?as?$inkey=>$inval)
????????echo?str_pad($inkey,30,".").str_pad($inval,20,".",STR_PAD_LEFT)."\n";
echo?"
";
---------------------輸出結(jié)果----------------------------------------

?????????????????????這是標(biāo)題?????????????????????
one..............................................1
two............................................155
three.........................................1679

---------------------------------------------------------------------
string?strtolower(string?subject)//轉(zhuǎn)換為小寫(xiě)
string?strtoupper(string?subject)//轉(zhuǎn)換為大寫(xiě)
string?ucfirst(string?subject)//首字母大寫(xiě)
string?ucwords(string?subject)//每個(gè)單詞首字母大寫(xiě)
string?ltrim(string?subject)//去左空白
string?rtrim(string?subject)//去右空白
string?trim(string?subject)去左右空白，空白包括null,制表符，換行符，回車(chē)符和空格
string?n12br(string?source)//將\n表示的換行符轉(zhuǎn)換為
標(biāo)記

3.字符串比較

integer?strcmp(sting?str1,string?str2)?//str1大于str2返回-1?str1小于str2返回1?str1和str2相等返回0?
integer?strmcmp(sting?str1,string?str2,integer?length)?//第三個(gè)參數(shù)限制length個(gè)字符的比較
print?strcmp("aardvark","aardwolf");
print?strncmp("aardvark","aardwolf",4);
---------------------輸出結(jié)果----------------------------------------
-10
---------------------------------------------------------------------
strcasecmp()和strncasecmp()是不區(qū)分大小寫(xiě)的比較函數(shù)

4.查找和抽取子字符串

string?substr(sting?source,integer?start[,integer?length])//從start開(kāi)始取length個(gè)字符
start和length可以使用負(fù)值
$var?=?"abcdefgh";
print?substr($var,2);//從0開(kāi)始計(jì)數(shù)
print?substr($var,2,3);
print?substr($var,-1);//從字符串的末尾開(kāi)始
print?substr($var,-5,2);
print?substr($var,-5,-2);
---------------------輸出結(jié)果----------------------------------------
cdefgh
cde
h
de
def
---------------------------------------------------------------------
integer?strpos(string?haystack,string?needle[,integer?offset])//查找子字符串的位置，返回第一次出現(xiàn).
integer?strrpos(string?haystack,string?needle)//只搜索單個(gè)字符（多個(gè)字符只取第一個(gè)），返回最后一次出現(xiàn)的索引.
還有常見(jiàn)的從?字符串中抽取找到的部分?的函數(shù)
string?strstr(string?haystack,string?needle)//不區(qū)分大小寫(xiě)
string?stristr(string?haystack,string?needle)//區(qū)分大小寫(xiě)
string?strrchr(string?haystack,sting?needle)
***********?array?explode(string?separator,string?subject[,integer?limit])//返回一個(gè)字符串?dāng)?shù)組
array?implode(string?glue,array?pieces)//返回一個(gè)字符串
///////////////////////////代碼段////////////////////////////////////////
$guest?=?"this?is?a?string";
$guestArray?=?explode("?",$guest);
var_dump($guestArray);
sort($guestArray);
echo?implode(",",$guestArray);
////////////////////////////////////////////////////////////////////////
---------------------輸出結(jié)果----------------------------------------
array(4)?{?[0]=>?string(4)?"this"?[1]=>?string(2)?"is"?[2]=>?string(1)?"a"?[3]=>?string(6)?"string"?}?a,is,string,this
---------------------------------------------------------------------

5.替換字符和子字符串

string?substr_replace(string?source,string?replace,int?start[,int?length])?