[英]replace the occurrence of character with a seq number using boost
How can i replace multiple occurrences of a character with a string containing the occurrence number. 如何用包含出现次数的字符串替换字符的多次出现。 eg if i have the following expression.
例如,如果我有以下表达式。
insert into emp values(?,?,?)
I want the following converted string. 我想要以下转换后的字符串。
insert into emp values(_p_1,_p_2,_p_3)
I am trying this using the boost regular expression. 我正在尝试使用boost正则表达式。
Can anyone tell me how to achieve this using the boost c++ (with no or minimum iteration). 谁能告诉我如何使用boost c ++(无迭代或最小迭代)实现这一目标。
currently I am using the following approach: 目前,我正在使用以下方法:
std::wstring q=L"insert into emp values(?,?,?)";
auto loc = q.find(L"?");
auto len = wcslen(L"?");
auto c=1;
while(loc != std::wstring::npos)
{
q.replace(loc, len , L"_p_"+to_wstring(c));
c++;
loc = q.find(L"?");
}
cout<<q.c_str();
Please suggest better and efficient approaches. 请提出更好,更有效的方法。
I'd just forget regular expressions and trying to do this simple thing with Boost. 我只是忘记了正则表达式,而是尝试使用Boost做这个简单的事情。
It's like asking, "how do I add 1 to a variable using Boost regular expressions"? 这就像问“如何使用Boost正则表达式将1加到变量中”?
Best answer, IMHO, is to instead just use ++
for the task of adding 1, and to use a loop to replace special characters with strings. 最好的答案,恕我直言,而是使用
++
来执行加1的任务,并使用循环将特殊字符替换为字符串。
string const query_format = "insert into emp values(?,?,?)";
string const params[] = {"_p_1", "_p_2", "_p3"};
string query;
string const* p = params;
for( char const c : query_format )
{
if( c == '?' ) { query += *p++; } else { query += c; }
}
// Use `query`
One might choose to wrap this up as a replace
function. 可以选择将其包装为
replace
功能。
Disclaimer: code not touched by compiler. 免责声明:编译器未触及的代码。
If you control the query_format
string, why not instead make the placeholders compatible with Boost format . 如果您控制
query_format
字符串,为什么不使占位符与Boost format兼容。
Re the parenthetical requirement 重新括号要求
” with no or minimum iteration
” ,没有迭代或迭代次数最少
there's iteration involved no matter how you do this. 无论您如何执行,都涉及迭代。 You can hide the iteration behind a function name, but that's all.
您可以将迭代隐藏在函数名称的后面,仅此而已。 It's logically impossible to actually avoid the iteration, and it's trivial (completely trivial) to hide it behind a function name.
从逻辑上讲,实际上避免迭代是不可能的,并且将其隐藏在函数名后面是微不足道的(完全琐碎的)。
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