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10. Caùc kí töï ñaëc bieät

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>>>Æ ñ Þóßÿ ?

Chuù yù:Neáu caùc kyù töï treân khoâng theå hieän caùc daáu nhaán hay caùc daáu phuï, thì coù nghóa laø web browser cuûa baïn khoâng hoå trôï boä kyù töï ISO. Baïn neân boû qua baøi naøy

Muïc ñích

Sau phaàn naøy baïn coù theå:

Söû duïng maõ HTML cho nhöõng kí töï ISO Latin 1 ñeå hieån thò nhöõng daáu nhaán cho nhöõng chöõ khoâng phaûi tieáng Anh (non-english letter).
Vieát nhöõng kí töï < and > trong HTML khi baïn caàn noù trong moät taøi lieäu.
Theâm nhöõng khoaûng traéng trong nhöõng chöõ vaø töø trong moät taøi lieäu

Baøi hoïc

Löu yù: Neáu baïn khoâng coù taøi lieäu töø nhöõng baøi hoïc tröôùc, baïn coù theå download ngay baây giôø.

Caùc daáu nhaán

Ñoâi khi coù theå baïn caàn söû duïng moät kí töï ñaëc bieät trong moät taøi lieäu HTML, moät daáu nhaán hay moät daáu phuï. Caùc daáu naøy ñaõ ñöôïc bieát ñeán theo ISO. Nhöõng kí töï ñaëc bieät nhö vaäy ñöôïc ñaùnh daáu trong HTML döôùi daïng:

   &xxxx;

Trong ñoù XXXX laø teân maõ (code name) cho kí töï ñaëc bieät ñoù.

Ví duï, trong phaàn "Terminology" cuûa baøi Volcano, chuùng ta muoán theâm moät söï giaûi thích cho moät thuaät ngöõ kyõ thuaät ñeå moâ taû moät loaïi rieâng bieät cuûa tieán trình buøng noå cuûa nuùi löûa. Thuaät ngöõ ñoù laø nuee ardente xuaát phaùt töø moät töø tieáng Phaùp vôùi nghóa laø "ñaùm maây noùng röïc" (glowing cloud) nhöng ñeå phaùt aâm ñuùng chuùng ta caàn moät daáu nhaán "saéc" (acute), ñeå töø ñoù xuaát hieän laø nuée ardente. Trong tröôøng hôïp naøy, chuùng ta thay theá chöõ e ñaàu tieân trong nuee baèng maõ HTML cuûa chöõ "e" coù daáu nhaán saéc é:

     nu&eacute;e ardente

Ñeå tham khaûo, haõy xem danh saùch caùc kyù töï ISO.

Baây giôø chuùng ta seõ theâm moät caâu vaøo taøi lieäu HTML cuûa chuùng ta maø caâu ñoù coù söû duïng moät kyù töï coù daáu nhaán:

Môû taäp tin HTML laø index.htm trong trình soaïn thaûo vaên baûn.
Beân döôùi danh saùch thuaät ngöõ cuûa phaàn Volcanology Terminology theâm vaøo:
```
 The term nu&eacute;e ardente, or 
 "glowing cloud" was first used by La Croix (1904)
 in his description of the volcanic flows he observed in 
 the 1902 eruption of Mt Pel&eacute;e, a historically 
 active volcano on the island of Martinique.
```
Chuù yù: Chuùng ta ñaõ söû duïng daáu nhaán saéc cho hai kyù töï "e" trong caâu naøy. Troâng coù veû laï quaù! Haõy chaéc chaén raèng baïn ñaõ thay kyù töï baèng chuoãi ñaõ vieát ôû treân ñeå hieån thò ñöôïc cuøng kyù töï ñoù vôùi daáu nhaán.
Löu vaø Reload laïi taäp tin HTML.

Escape Sequences cuûa HTML

HTML cho daáu nhaán laø moät ví duï cuûa moät lôùp caùc tag toång quaùt hôn ñöôïc goïi laø escape sequences. Trong quaù trình nhaäp vaên baûn HTML cho ñeán giôø, baïn coù theå töï hoûi chuùng ta seõ laøm gì khi caàn söû duïng moät daáu < (nhoû hôn) hoaëc moät daáu > (lôùn hôn)? Hai kyù töï naøy cuõng vôùi daáu & (vaø) coù moät yù nghóa ñaëc bieät trong HTML vaø khoâng theå söû duïng nhö moät kyù töï ñaùnh vaøo ñöôïc. Thay vì ñaùnh tröïc tieáp chuùng, haõy söû duïng escape sequences:

   &lt;  thay cho <
   &gt;  thay cho > 
   &amp; thay cho &

Baây giôø chuùng ta haõy aùp duïng caùc kyù hieäu naøy trong baøi Volcano cuûa chuùng ta. Trong baøi tröôùc: chuùng ta ñaõ theâm moät baûng lieät keâ vaøi nuùi löûa cuøng vôùi khoái löôïng vaät chaát ñaõ phun ra töø chuùng. Chuùng ta noùi raèng moät trong nhöõng soá lieäu (500-600) cho Long Valley laø khoâng ñöôïc chính xaùc laém (thoâng thöôøng ñaây laø caùc giaù trò gaàn ñuùng), vaø chuùng ta muoán söûa ñoåi trò naøy thaønh >450 & <700. Ñeå laøm ñieàu naøy:

Môû taäp tin HTML index.htm trong trình soaïn thaûo
Beân döôùi tieâu ñeà Volumes of Some Well-Known Volcanic Eruptions, tìm doøng Long Valley trong baûng:
```
Long Valley, California   pre-historic    500 - 600
```
vaø ñoåi noù thaønh:
```
Long Valley, California   pre-historic  &gt;450 &amp; &lt;700
```
Chuù yù: Maëc daàu chuùng ta söû duïng escape sequences beân trong moät preformatted text, haõy chuù yù moät web browser vaãn thoâng dòch ñuùng vaø hieån thò caùc kyù töï ñaëc bieät naøy. Nhö vaäy, escape sequences coù theå söû duïng trong moïi phaàn cuûa moät taøi lieäu HTML keå caû caùc tieâu ñeà vaø lieân keát anchor.
Löu vaø Reload taäp tin HTML

Nhöõng khoaûng troáng theâm vaøo

Nhö baïn ñaõ thaáy moät web browser seõ boû qua taát caû nhöõng khoaûng traéng khoâng lieân quan trong taäp tin HTML cuûa baïn. Tuy nhieân, coù nhöõng luùc thaät söï chuùng ta muoán coù nhieàu hôn moät khoaûng traéng . Khi naøo vaäy? Moät vaøi ngöôøi thích coù hai khoaûng traéng theo sau moät daáu chaám heát caâu. Neáu baïn muoán thuït vaøo caâu ñaàu tieân cuûa moãi ñoaïn vaên baïn seõ laøm sao? Laøm theá naøo ñeå coù moät töø ñôn ôû vò trí caùch xa phaàn coøn laïi? Moät maõ HTML daønh cho vieäc theâm vaøo moät kí töï traéng laø kí töï ñaëc bieät ñöôïc goïi laø "khoaûng traéng khoâng bò phaù huûy" (non-breaking space):

  &nbsp;

Sau ñaây laø moät vaøi ví duï veà caùch söû duïng khoaûng traéng khoâng bò phaù huûy:

HTML Keát quaû

Khoaûng traéng khoâng bò phaù huûy ñöôïc duøng ñeå traûi daøi caùc kyù töï trong moät töø

<tt> C   H   E   E   S   E </tt>
C H E E S E

Hai khoaûng traéng khoâng bò phaù huûy ñöôïc duøng ñeå thuït caùc caâu ñaàu cuûa ñoaïn vaên vaøo trong

    When Sir Longhorn had tragically died, no one was left to carry on his tradition. There was much sadness in the land. And no cheese.     But then the young genius Sheila Colby discovered the missing ingredient. And once again, cheese was plentiful.
When Sir Longhorn had tragically died, no one was left to carry on his tradition. There was much sadness in the land. And no cheese.
But then the young genius Sheila Colby discovered the missing ingredient. And once again, cheese was plentiful.

Moät khoaûng traéng nöõa ñöôïc theâm vaøo sau cuoái moãi caâu

    When Sir Longhorn had tragically died, no one was left to carry on his tradition.   There was much sadness in the land.   And no cheese.     But then the young genius Sheila Colby discovered the missing ingredient.   And once again, cheese was plentiful.
When Sir Longhorn had tragically died, no one was left to carry on his tradition. There was much sadness in the land. And no cheese.
But then the young genius Sheila Colby discovered the missing ingredient. And once again, cheese was plentiful.

HTML	Keát quaû
Khoaûng traéng khoâng bò phaù huûy ñöôïc duøng ñeå traûi daøi caùc kyù töï trong moät töø
<b><tt> C   H   E   E   S   E </tt></b>	`C H E E S E`
Hai khoaûng traéng khoâng bò phaù huûy ñöôïc duøng ñeå thuït caùc caâu ñaàu cuûa ñoaïn vaên vaøo trong
When Sir Longhorn had tragically died, no one was left to carry on his tradition. There was much sadness in the land. And no cheese. <p>     But then the young genius Sheila Colby discovered the missing ingredient. And once again, cheese was plentiful.	When Sir Longhorn had tragically died, no one was left to carry on his tradition. There was much sadness in the land. And no cheese. But then the young genius Sheila Colby discovered the missing ingredient. And once again, cheese was plentiful.
Moät khoaûng traéng nöõa ñöôïc theâm vaøo sau cuoái moãi caâu
When Sir Longhorn had tragically died, no one was left to carry on his tradition.   There was much sadness in the land.   And no cheese. <p>     But then the young genius Sheila Colby discovered the missing ingredient.   And once again, cheese was plentiful.	When Sir Longhorn had tragically died, no one was left to carry on his tradition. There was much sadness in the land. And no cheese. But then the young genius Sheila Colby discovered the missing ingredient. And once again, cheese was plentiful.

Coù theå baïn muoán coù kinh nghieäm vôùi caùc caùch söû duïng khaùc nhau cho khoaûng traéng khoâng bò phaù huûy. Baây giôø, chuùng ta seõ khoâng söûa caùc taøi lieäu HTML cuûa chuùng ta, nhöng neáu muoán, baïn coù theå theâm nhöõng maõ ñeå laøm thuït ñaàu doøng caùc caâu môû ñaàu cuûa taát caû caùc ñoaïn vaên qua vieäc söû duïng hai laàn maõ khoaûng traéng khoâng bò phaù huûy.

Kieåm tra laïi coâng vieäc cuûa baïn

So saùnh trang Web cuûa baïn vôùi ví duï maãu ñeå bieát taøi lieäu neân xuaát hieän nhö theá naøo. Neáu trang web cuûa baïn khoâng gioáng nhö ví duï maãu, haõy kieåm tra laïi vaên baûn baïn ñaõ ñaùnh trong trình soaïn thaûo. Haõy baûo ñaûm baïn vieát ñuùng caùc escape sequence vôùi kyù töï & vaø ;

Thoâng tin boå sung

Döôùi ñaây laø moät vaøi kí töï ñaëc bieät coù theå höõu ích cho baïn:

Teân	HTML	Keát quaû
Copyright	`©`	©
Trademark	`®`	®

Xem laïi

Nhöõng vaán ñeà neân xem laïi trong baøi naøy:

Trong HTML, caùch naøo ñeå hieån thò kí töï tieáng Ñöùc "umlaut" (ü)?
Ñieàu gì seõ xaûy ra neáu baïn khoâng söû duïng moät escape sequence cho < and >?
Taïi sao caàn moät escape sequence cho kí töï &?
Laøm theá naøo coù theå thuït caùc ñoaïn vaên vaøo trong?

Thöïc taäp töï do

Trong vaên baûn HTML cuûa rieâng baïn, theâm vaøo moät töø nöôùc ngoaøi maø töø ñoù caàn moät daáu nhaán ñaët bieät, hay theâm vaøo moät bieåu thöùc toaùn hoïc coù söû duïng daáu < hay daáu >. Hoaëc laø baïn coù theå theâm caùc khoaûng traéng ñeå thuït caùc ñoaïn vaên vaøo trong.

Ñeán phaàn keá tieáp ....

Xaây döïng moät danh muïc saùch söû duïng moät danh saùch moâ taû.

ÑEÁN.... | Muïc Luïc | Baøi tröôùc: "Preformatted Text" | Baøi keá: "Danh saùch moâ taû" |

Soaïn thaûo HTML Baøi 10: Caùc kyù töï Ñaëc bieät

The Internet Connection at MCLI is Alan Levine --}
Comments to levine@maricopa.edu

URL: http://www.mcli.dist.maricopa.edu/tut/tut10.html