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1ãQStringä¹éè½½ç+å+=è¿ç®ç¬¦ãè¿ä¸¤ä¸ªè¿ç®ç¬¦å¯ä»¥æ两个å符串è¿æ¥å°ä¸èµ·ã
2ãQStringçappend()å½æ°åæä¾äºç±»ä¼¼çæä½ï¼ä¾å¦ï¼
str = "User: ";
str.append(userName);
str.append("\n");
äºãè·åå符串æä½ç½®çå¼ã
QString x = "Nine pineapples";
QString y = x.mid(5, 4); // y == "pine"
QString z = x.mid(5); // z == "pineapples"
1ãmid()å½æ°æ¥å两个åæ°ï¼ç¬¬ä¸ä¸ªæ¯èµ·å§ä½ç½®ï¼ç¬¬äºä¸ªæ¯å串çé¿åº¦ãå¦æçç¥ç¬¬äºä¸ªåæ°ï¼åä¼ä»èµ·å§ä½ç½®æªåå°æ«å°¾ãæ£å¦ä¸é¢çä¾åæ¾ç¤ºçé£æ ·
2ãå½æ°left()årigt()类似ï¼é½æ¥åä¸ä¸ªintç±»åçåæ°nï¼é½æ¯å¯¹å符串è¿è¡æªåãä¸åä¹å¤å¨äºï¼left()å½æ°ä»å·¦ä¾§æªån个å符ï¼èright()ä»å³ä¾§å¼å§æªåãä¸é¢æ¯left()çä¾åï¼
1. QString x = "Pineapple";
2. QString y = x.left(4); // y == "Pine"
ä¸ãè·åå符å¨å符ä¸çä½ç½®ã
indexOf()
QString x = "sticky question";
QString y = "sti";
x.indexOf(y); // returns 0
x.indexOf(y, 1); // returns 10
x.indexOf(y, 10); // returns 10
x.indexOf(y, 11); // returns -1
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startsWith() endsWith()
if (url.startsWith("http:") && url.endsWith(".png"))
{ }
è¿æ®µä»£ç çä»·äº
if (url.left(5) == "http:" && url.right(4) == ".png")
{ }
äºãå符串æ¿æ¢å½æ°replace();
trimmed()å½æ°å»é¤å符串两侧ç空ç½å符(注æï¼ç©ºç½å符å
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ä»
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toLower()åtoUpper()å½æ°ä¼å°å符串转æ¢æå°å大åå符串ï¼
remove()å insert()å½æ°æä¾äºå é¤åæå
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simplified()å½æ°å¯ä»¥å°ä¸²ä¸çææè¿ç»ç空ç½å符æ¿æ¢æä¸ä¸ªï¼å¹¶ä¸æ两端ç空ç½å符å»é¤ï¼ä¾å¦" \t âä¼è¿åä¸ä¸ªç©ºæ ¼" "ã
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ãconst char *ç±»åçCé£æ ¼å符串ä¸QStringå符ä¹é´ç转æ¢ã
ç®åæ¥è¯´ï¼QStringç+=å³å¯å®æè¿ä¸ªåè½ï¼
str += " (1870)";
è¿éï¼æ们å°const char * ç±»åçå符串" (1870)"转æ¢æ为QStringç±»åã
å¦æéè¦æ¾å¼ç转æ¢ï¼å¯ä»¥ä½¿ç¨QStringç强å¶è½¬æ¢æä½ï¼æè
æ¯ä½¿ç¨å½æ°fromAscii()çã
为äºå°QStringç±»å转æconst char *å符串ï¼éè¦è¿è¡ä¸¤æ¥æä½ï¼ä¸æ¯ä½¿ç¨toAscii()è·å¾ä¸ä¸ªQByteArrayç±»å对象ï¼
ç¶åè°ç¨å®çdata()æè
constData()å½æ°ï¼
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printf("User: %s\n", str.toAscii().data());
为äºæ¹ä¾¿ä½¿ç¨ï¼Qtæä¾äºä¸ä¸ªå®qPrintable()ï¼è¿ä¸ªå®çä»·äºtoAscii().constData()ï¼ä¾å¦ï¼
printf("User: %s\n", qPrintable(str));
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constData()å½æ°ï¼å°è·å¾QByteArray å
é¨çä¸ä¸ªconst char*ç±»åçå符串ï¼
å æ¤ï¼æ们ä¸éè¦æ
å¿å
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åãä¸è¿è¿ä¹æ示æ们ï¼æ³¨æä¸è¦ä½¿ç¨è¿ä¸ªæé太é¿æ¶é´ï¼
å 为å¦æ QByteArray被deleteï¼é£ä¹è¿ä¸ªæéä¹å°±æ为éæéäºãå¦æè¿ä¸ªQByteArray对象没æ被æ¾å¨ä¸ä¸ªåéä¸ï¼
é£ä¹å½è¯å¥ç»æåï¼QbyteArray对象就ä¼è¢«deleteï¼è¿ä¸ªæéä¹å°±è¢«delete äºã
ä¸ãå符串ä¸å
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toInt() 转æ´å
toDouble() 转å精度å
toLong() 转é¿æ´å
è¿äºå½æ°é½æ¥åä¸ä¸ªboolæéä½ä¸ºåæ°ï¼å½æ°ç»æä¹åå°æ ¹æ®æ¯å¦è½¬æ¢æå设置为trueæè
falseï¼
bool ok;
double d = str.toDouble(&ok);
if(ok)
{
// do something...
} else {
// do something...
}
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1ã使ç¨staticçå½æ°number()å¯ä»¥ææ°å转æ¢æå符串ãä¾å¦ï¼
QString str = QString::number(54.3);
2ã ä¹å¯ä»¥ä½¿ç¨éstaticå½æ°setNum()æ¥å®ç°ç¸åçç®çï¼
QString str;
str.setNum(54.3);
å
«ãQStringåæä¾äºä¸ä¸ªsprintf()å½æ°å®ç°äºä¸Cè¯è¨ä¸çprintfå½æ°ç¸åçåè½ã
1. str.sprintf("%s %.1f%%", "perfect competition", 100.0);
è¿å¥ä»£ç å°è¾åºï¼perfect competition 100.0%
2ãå¦ä¸ç§æ ¼å¼åå符串è¾åºçå½æ°arg():
str = QString("%1 %2 (%3s-%4s)").arg("permissive").arg("society").arg(1950).arg(1970);
è¿æ®µä»£ç ä¸ï¼%1, %2, %3, %4ä½ä¸ºå ä½ç¬¦ï¼å°è¢«åé¢çarg()å½æ°ä¸çå
容ä¾æ¬¡æ¿æ¢ï¼æ¯å¦%1å°è¢«æ¿æ¢æpermissiveï¼
%2å°è¢«æ¿æ¢æsocietyï¼%3å°è¢«æ¿æ¢æ 1950ï¼%4å°è¢«æ¿æ¢æ¾1970ï¼æåï¼
è¿å¥ä»£ç è¾åºä¸ºï¼permissive society (1950s-1970s). arg()å½æ°æ¯èµ·sprintf()æ¥æ¯ç±»åå®å
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length();
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