//1、建立常量字串。
nsstring *astring = @"this is a string!";
//2、建立空字串，給予賦值。
nsstring *astring = [[nsstring alloc] init];
astring = @"this is a string!";
nslog(@"astring:%@",astring);
[astring release];
//3、在以上方法中，提公升速度:initwithstring方法
nsstring *astring = [[nsstring alloc] initwithstring:@"this is a string!"];
nslog(@"astring:%@",astring);
[astring release];
//4、用標準c建立字串:initwithcstring方法
char *cstring = "this is a string!";
nsstring *astring = [[nsstring alloc] initwithcstring:cstring];
nslog(@"astring:%@",astring);
[astring release];
//5、建立格式化字串:佔位符（由乙個%加乙個字元組成）
int i = 1;
int j = 2;
nsstring *astring = [[nsstring alloc] initwithstring:[nsstring stringwithformat:@"%d.this is %i string!",i,j]];
nslog(@"astring:%@",astring);
[astring release];
//6、建立臨時字串
nsstring *astring;
astring = [nsstring stringwithcstring:"this is a temporary string"];
nslog(@"astring:%@",astring);
nsstring *path = @"astring.text";
nsstring *astring = [[nsstring alloc] initwithcontentsoffile:path];
nslog(@"astring:%@",astring);
[astring release];
nsstring *astring = [[nsstring alloc] initwithstring:@"this is a string!"];
nslog(@"astring:%@",astring);
nsstring *path = @"astring.text";
[astring writetofile: path atomically: yes];
[astring release];
//用c比較:strcmp函式
char string1 = "string!";
char string2 = "string!";
if(strcmp(string1, string2) = = 0)
//isequaltostring方法
nsstring *astring01 = @"this is a string!";
nsstring *astring02 = @"this is a string!";
bool result = [astring01 isequaltostring:astring02];
nslog(@"result:%d",result);
//compare方法(comparer返回的三種值)
nsstring *astring01 = @"this is a string!";
nsstring *astring02 = @"this is a string!";
bool result = [astring01 compare:astring02] = = nsorderedsame;
nslog(@"result:%d",result);
//nsorderedsame 判斷兩者內容是否相同
nsstring *astring01 = @"this is a string!";
nsstring *astring02 = @"this is a string!";
bool result = [astring01 compare:astring02] = = nsorderedascending;
nslog(@"result:%d",result);
//nsorderedascending 判斷兩物件值的大小(按字母順序進行比較，astring02大於astring01為真)
nsstring *astring01 = @"this is a string!";
nsstring *astring02 = @"this is a string!";
bool result = [astring01 compare:astring02] = = nsordereddescending;
nslog(@"result:%d",result);
//nsordereddescending 判斷兩物件值的大小(按字母順序進行比較，astring02小於astring01為真)
//不考慮大 小寫比較字串1
nsstring *astring01 = @"this is a string!";
nsstring *astring02 = @"this is a string!";
bool result = [astring01 caseinsensitivecompare:astring02] = = nsorderedsame;
nslog(@"result:%d",result);
//nsordereddescending判斷兩物件值的大小(按字母順序進行比較，astring02小於astring01為真)
//如何判斷字串為空
nsstring *urlstring = [urlinput stringvalue];
if (!urlstring) else else
} }
convert nsstring to int
1nsstring*anumberstring =@"123";
2inti = [anumberstring intvalue];
convert int to nsstring
1intanumber = 123;
2nsstring*astring = [nsstringstringwithformat:@"%d", anumber];
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