如何找出字符串中的第一個字符是否是拉丁字母的字母

Question

我有一個帶有字符串的數組。檢查數組中每個字符串的第一個字符是否來自拉丁字母的最佳方法是什麼？

Answer 1

基本上你可以使用的字符集，像這樣：

NSString* string = @"This is a string"; 
NSCharacterSet *letters = [NSCharacterSet letterCharacterSet]; 
if([letters characterIsMember:[string characterAtIndex:0]]) { 
    // This is a letter 
} 

的例子是不言而喻的:-)

Answer 2

這取決於如果你要處理的Objective-C對象或C（我假定目標C，但可讓兩者都做）

Objective-C的 - 該數組是NSArrayNSStrings的：

1. 取第一項：NSString *firstString = [array objectAtIndex:0];
2. 取得一個字母的範圍：`NSRange lettersRange = [firstString rangeOfCharacterFromSet：[NSCharacterSet letterCharacterSet];
3. 檢查範圍起始於字符串的開始：BOOL isFirstCharALetter = lettersRange.location = 0;

c - 接收陣列的char *（即char *[]）的陣列：

1. 讀取第一項：char *firstString = strings[0];
2. 獲取字符串的第一個字符：char firstChar = firstString[0];
3. 檢查的第一個字符是ASCII字符的字母範圍：BOOL isFirstCharALetter = (firstChar >= 'A' && firstChar <='Z') || (firstChar >= 'a' && firstChar <='z');

Answer 3

簡單oneliner：

if ([string length] && iswalpha([string characterAtIndex:0])) 
{ 
    // stuff 
} 

Answer 4

//Defines only alphabet that we will compare with 
NSCharacterSet *alphaBetFromAToZ = [NSCharacterSet letterCharacterSet]; 
NSCharacterSet *numberFrom0To9 = [NSCharacterSet decimalDigitCharacterSet]; 

//My string 
NSString *myStringToCheck = @"String"; 

//Check if string is not empty and if so, make it a not empty string otherwise the app could throw up an exception 
myStringToCheck = ([myStringToCheck length] == 0) ? @" ":myStringToCheck; 

//Check if first string is from the alphabet 
if ([alphaBetFromAToZ characterIsMember:[myStringToCheck characterAtIndex:0]]) 
{ 
    //First character is from the alphabet 
} 
else if ([numberFrom0To9 characterIsMember:[myStringToCheck characterAtIndex:0]]) 
{ 
    //First character is a number 
} 
else 
{ 
    //First character is NOT from the alphabet and also is not a number, is something like @ [ ] $ %^...... 
}