//随机生成一个128位的字符串
+ (NSString *)randomStringWith128
{
int num = arc4random() % 128 + 1;
char *s = genRandomChar(num);
NSString *rString = [NSString stringWithCString:s encoding:NSUTF8StringEncoding];
free(s);
return rString;
}
char* genRandomChar(int length)
{
int flag, i;
char* string;
srand((unsigned) time(NULL ));
if ((string = (char*) malloc(length)) == NULL )
{
return NULL ;
}
for (i = 0; i < length - 1; i++)
{
flag = rand() % 3;
switch (flag)
{
case 0:
string[i] = 'A' + rand() % 26;
break;
case 1:
string[i] = 'a' + rand() % 26;
break;
case 2:
string[i] = '0' + rand() % 10;
break;
default:
string[i] = 'x';
break;
}
}
string[length - 1] = ' ';
return string;
}