关于isalpha的使用

 在Thinking C++ 中

while(!isalpha(*p) && p != end)
p++;
// Copy until the first non-alpha character:
while (isalpha(*p) && p != end)

 

should be

 

while( p != end && !isalpha((unsigned char)*p) )
            p++;
        // Copy until the first non-alpha character:
        while (p != end && isalpha((unsigned char)*p))

 

isalpha只接受unsigned char的参数，如果是负数就会出错。