本文整理汇总了C++中std::basic_string::at方法的典型用法代码示例。如果您正苦于以下问题：C++ basic_string::at方法的具体用法？C++ basic_string::at怎么用？C++ basic_string::at使用的例子？那么, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类std::basic_string的用法示例。
在下文中一共展示了basic_string::at方法的1个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的C++代码示例。
示例1: sep
inline
time_duration
str_from_delimited_time_duration(const std::basic_string<char_type>& s)
{
unsigned short min=0, sec =0;
int hour =0;
bool is_neg = (s.at(0) == '-');
boost::int64_t fs=0;
int pos = 0;
typedef typename std::basic_string<char_type>::traits_type traits_type;
typedef boost::char_separator<char_type, traits_type> char_separator_type;
typedef boost::tokenizer<char_separator_type,
typename std::basic_string<char_type>::const_iterator,
std::basic_string<char_type> > tokenizer;
typedef typename boost::tokenizer<char_separator_type,
typename std::basic_string<char_type>::const_iterator,
typename std::basic_string<char_type> >::iterator tokenizer_iterator;
char_type sep_chars[5] = {'-',':',',','.'};
char_separator_type sep(sep_chars);
tokenizer tok(s,sep);
for(tokenizer_iterator beg=tok.begin(); beg!=tok.end();++beg){
switch(pos) {
case 0: {
hour = boost::lexical_cast<int>(*beg);
break;
}
case 1: {
min = boost::lexical_cast<unsigned short>(*beg);
break;
}
case 2: {
sec = boost::lexical_cast<unsigned short>(*beg);
break;
};
case 3: {
int digits = static_cast<int>(beg->length());
//Works around a bug in MSVC 6 library that does not support
//operator>> thus meaning lexical_cast will fail to compile.
#if (defined(BOOST_MSVC) && (_MSC_VER < 1300))
// msvc wouldn't compile 'time_duration::num_fractional_digits()'
// (required template argument list) as a workaround a temp
// time_duration object was used
time_duration td(hour,min,sec,fs);
int precision = td.num_fractional_digits();
// _atoi64 is an MS specific function
if(digits >= precision) {
// drop excess digits
fs = _atoi64(beg->substr(0, precision).c_str());
}
else {
fs = _atoi64(beg->c_str());
}
#else
int precision = time_duration::num_fractional_digits();
if(digits >= precision) {
// drop excess digits
fs = boost::lexical_cast<boost::int64_t>(beg->substr(0, precision));
}
else {
fs = boost::lexical_cast<boost::int64_t>(*beg);
}
#endif
if(digits < precision){
// trailing zeros get dropped from the string,
// "1:01:01.1" would yield .000001 instead of .100000
// the power() compensates for the missing decimal places
fs *= power(10, precision - digits);
}
break;
}
default: break;
}//switch
pos++;
}
if(is_neg) {
return -time_duration(hour, min, sec, fs);
}
else {
return time_duration(hour, min, sec, fs);
}
}